blocks|key|3889652|text|您需要使用Range<String.Index>而不是传统的NSRange。我这样做的方法(也许还有更好的方法)是将字符串的String.Index与advance一起移动。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3889653|我不知道你想要替换什么范围，但让我们假设你想替换前两个字符。|3889654|var+start+=+textField.text.startIndex+//+Start+at+the+string's+start+index
var+end+=+advance(textField.text.startIndex,+2)+//+Take+start+index+and+advance+2+characters+forward
var+range:+Range<String.Index>+=+Range<String.Index>(start:+start,end:+end)

textField.text.stringByReplacingCharactersInRange(range,+withString:+string)|code-block|syntax|javascript|3889655|entityMap^0|5|J|U|7|1Q|C|23|7|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|N|$]]

You need to use <code>Range&lt;String.Index&gt;</code> instead of the classic <code>NSRange</code>. The way I do it (maybe there is a better way) is by taking the string's <code>String.Index</code> a moving it with <code>advance</code>.

I don't know what range you are trying to replace, but let's pretend you want to replace the first 2 characters.

<pre><code>var start = textField.text.startIndex // Start at the string's start index
var end = advance(textField.text.startIndex, 2) // Take start index and advance 2 characters forward
var range: Range&lt;String.Index&gt; = Range&lt;String.Index&gt;(start: start,end: end)

textField.text.stringByReplacingCharactersInRange(range, withString: string)
</code></pre>

blocks|key|3889723|text|@Emilie对伟大答案的评论，而不是替代/竞争的答案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3889724|(Xcode6+6-Beta5+5)|3889725|var+original++++=+"This+is+a+test"
var+replacement+=+"!"

var+startIndex+=+advance(original.startIndex,+1)+//+Start+at+the+second+character
var+endIndex+++=+advance(startIndex,+2)+//+point+ahead+two+characters
var+range++++++=+Range(start:startIndex,+end:endIndex)
var+final+=+original.stringByReplacingCharactersInRange(range,+withString:replacement)

println("start+index:+\(startIndex)")
println("end+index:+++\(endIndex)")
println("range:+++++++\(range)")
println("original:++++\(original)")
println("final:+++++++\(final)")|code-block|syntax|javascript|3889726|输出：|3889727|start+index:+4
end+index:+++7
range:+++++++4..<7
original:++++This+is+a+test
final:+++++++!his+is+a+test|3889728|注意，索引帐户包含多个代码单元。旗(区号符号字母ES)为8字节，(JOY的眼泪面)为4字节。(在这种特殊情况下，UTF-8、UTF-16和UTF-32表示的字节数是相同的。)|3889729|把它包裹在一个漏斗里：|3889730|func+replaceString(#string:String,+#with:String,+#start:Int,+#length:Int)+->String+{
++++var+startIndex+=+advance(original.startIndex,+start)+//+Start+at+the+second+character
++++var+endIndex+++=+advance(startIndex,+length)+//+point+ahead+two+characters
++++var+range++++++=+Range(start:startIndex,+end:endIndex)
++++var+final+=+original.stringByReplacingCharactersInRange(range,+withString:+replacement)
++++return+final
}

var+newString+=+replaceString(string:original,+with:replacement,+start:1,+length:2)
println("newString:\(newString)")|3889731|3889732|newString:+!his+is+a+test|3889733|entityMap^0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Y|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Z|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|10|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|11|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|12|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|13|8|@]|9|@]|A|$]]|$1|Q|3|R|5|F|7|14|8|@]|9|@]|A|$G|H]]|$1|S|3|J|5|6|7|15|8|@]|9|@]|A|$]]|$1|T|3|U|5|F|7|16|8|@]|9|@]|A|$G|H]]|$1|V|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|W|$]]

A riff on the great answer by @Emilie, not a replacement/competing answer. 
(Xcode6-Beta5)

<pre><code>var original = "This is a test"
var replacement = "!"

var startIndex = advance(original.startIndex, 1) // Start at the second character
var endIndex = advance(startIndex, 2) // point ahead two characters
var range = Range(start:startIndex, end:endIndex)
var final = original.stringByReplacingCharactersInRange(range, withString:replacement)

println("start index: \(startIndex)")
println("end index: \(endIndex)")
println("range: \(range)")
println("original: \(original)")
println("final: \(final)")
</code></pre>

Output: 

<pre><code>start index: 4
end index: 7
range: 4..&lt;7
original: This is a test
final: !his is a test
</code></pre>

Notice the indexes account for multiple code units. The flag (REGIONAL INDICATOR SYMBOL LETTERS ES) is 8 bytes and the (FACE WITH TEARS OF JOY) is 4 bytes. (In this particular case it turns out that the number of bytes is the same for UTF-8, UTF-16 and UTF-32 representations.)

Wrapping it in a func:

<pre><code>func replaceString(#string:String, #with:String, #start:Int, #length:Int) -&gt;String {
 var startIndex = advance(original.startIndex, start) // Start at the second character
 var endIndex = advance(startIndex, length) // point ahead two characters
 var range = Range(start:startIndex, end:endIndex)
 var final = original.stringByReplacingCharactersInRange(range, withString: replacement)
 return final
}

var newString = replaceString(string:original, with:replacement, start:1, length:2)
println("newString:\(newString)")
</code></pre>

Output: 

<pre><code>newString: !his is a test
</code></pre>

blocks|key|3592453|text|String的NSString版本(相对于Swift字符串)接受NSRange，因此一个简单的解决方案是将转换为+NSString+first。在Swift+3和2中，委托和替换方法名称略有不同，因此取决于您使用的Swift：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|3592454|Swift+3.0|3592455|func+textField(_+textField:+UITextField,
+++++++++++++++shouldChangeCharactersIn+range:+NSRange,
+++++++++++++++replacementString+string:+String)+->+Bool+{

++let+nsString+=+textField.text+as+NSString?
++let+newString+=+nsString?.replacingCharacters(in:+range,+with:+string)
}|code-block|syntax|javascript|3592456|Swift+2.x|3592457|func+textField(textField:+UITextField,
+++++++++++++++shouldChangeCharactersInRange+range:+NSRange,
+++++++++++++++replacementString+string:+String)+->+Bool+{

++++let+nsString+=+textField.text+as+NSString?
++++let+newString+=+nsString?.stringByReplacingCharactersInRange(range,+withString:+string)
}|3592458|entityMap^0|0|6|1H|3|1L|8|1U|5|0|6|7|8|W|7|1L|8|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]|$9|W|A|X|B|C]|$9|Y|A|Z|B|C]|$9|10|A|11|B|C]|$9|12|A|13|B|D]|$9|14|A|15|B|D]|$9|16|A|17|B|D]|$9|18|A|19|B|D]]|E|@]|F|$]]|$1|G|3|H|5|6|7|1A|8|@]|E|@]|F|$]]|$1|I|3|J|5|K|7|1B|8|@]|E|@]|F|$L|M]]|$1|N|3|O|5|6|7|1C|8|@]|E|@]|F|$]]|$1|P|3|Q|5|K|7|1D|8|@]|E|@]|F|$L|M]]|$1|R|3|-4|5|6|7|1E|8|@]|E|@]|F|$]]]|S|$]]

The <code>NSString</code> version (as opposed to Swift String) of <code>replacingCharacters(in: NSRange, with: NSString)</code> accepts an <code>NSRange</code>, so one simple solution is to convert <code>String</code> to <code>NSString</code> first. The delegate and replacement method names are slightly different in Swift 3 and 2, so depending on which Swift you're using:

<h3>Swift 3.0</h3>

<pre><code>func textField(_ textField: UITextField,
 shouldChangeCharactersIn range: NSRange,
 replacementString string: String) -&gt; Bool {

 let nsString = textField.text as NSString?
 let newString = nsString?.replacingCharacters(in: range, with: string)
}
</code></pre>

<h3>Swift 2.x</h3>

<pre><code>func textField(textField: UITextField,
 shouldChangeCharactersInRange range: NSRange,
 replacementString string: String) -&gt; Bool {

 let nsString = textField.text as NSString?
 let newString = nsString?.stringByReplacingCharactersInRange(range, withString: string)
}
</code></pre>

blocks|key|3889808|text|然而，由于您具体询问了如何将NSRange转换为Range<String.Index>，因此这与艾米莉的回答类似，您可以这样做：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3889809|func+textField(textField:+UITextField,+shouldChangeCharactersInRange+range:+NSRange,+replacementString+string:+String)+->+Bool+{

+++++let+start+=+advance(textField.text.startIndex,+range.location)+
+++++let+end+=+advance(start,+range.length)+
+++++let+swiftRange+=+Range<String.Index>(start:+start,+end:+end)+
+++++...

}|code-block|syntax|javascript|3889810|entityMap^0|E|7|O|J|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

This is similar to Emilie's answer however since you asked specifically how to convert the <code>NSRange</code> to <code>Range&lt;String.Index&gt;</code> you would do something like this:

<pre><code>func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -&gt; Bool {

 let start = advance(textField.text.startIndex, range.location) 
 let end = advance(start, range.length) 
 let swiftRange = Range&lt;String.Index&gt;(start: start, end: end) 
 ...

}
</code></pre>

blocks|key|3889879|text|这是我最大的努力。但这不能检查或检测错误的输入参数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3889880|extension+String+{
++++///+:r:+Must+correctly+select+proper+UTF-16+code-unit+range.+Wrong+range+will+produce+wrong+result.
++++public+func+convertRangeFromNSRange(r:NSRange)+->+Range<String.Index>+{
++++++++let+a+++=+++(self+as+NSString).substringToIndex(r.location)
++++++++let+b+++=+++(self+as+NSString).substringWithRange(r)

++++++++let+n1++=+++distance(a.startIndex,+a.endIndex)
++++++++let+n2++=+++distance(b.startIndex,+b.endIndex)

++++++++let+i1++=+++advance(startIndex,+n1)
++++++++let+i2++=+++advance(i1,+n2)

++++++++return++Range<String.Index>(start:+i1,+end:+i2)
++++}
}

let+s+++=+++""
println(s[s.convertRangeFromNSRange(NSRange(location:+4,+length:+2))])++++++//++Proper+range.+Produces+correct+result.
println(s[s.convertRangeFromNSRange(NSRange(location:+0,+length:+4))])++++++//++Proper+range.+Produces+correct+result.
println(s[s.convertRangeFromNSRange(NSRange(location:+0,+length:+2))])++++++//++Improper+range.+Produces+wrong+result.
println(s[s.convertRangeFromNSRange(NSRange(location:+0,+length:+1))])++++++//++Improper+range.+Produces+wrong+result.|code-block|syntax|javascript|3889881|结果。|3889882|3889883|详细信息|3889884|NSRange来自NSString计数UTF-16代码单元_s和Range<String.Index>来自Swift+String是一个_opaque相对类型，它只提供平等和导航操作。这是有意隐藏的设计。|offset|length|style|CODE|3889885|虽然Range<String.Index>似乎被映射到UTF-16代码单元偏移量，但这只是一个实现细节，我找不到任何关于保证的内容。这意味着实现细节可以随时更改。Swift+String的内部表示没有很好的定义，我不能依赖它。|3889886|NSRange值可以直接映射到String.UTF16View索引。但是没有方法将其转换为String.Index。|3889887|Swift+String.Index是迭代Swift+Character的索引，它是一个Unicode字素簇。然后，您必须提供正确的NSRange来选择正确的字素簇。如果像上面的例子那样提供错误的范围，就会产生错误的结果，因为无法计算出正确的字素聚类范围。|3889888|如果保证String.Index是UTF-16码单元偏移量，那么问题就变得简单了.但这不太可能发生。|3889889|逆转换|3889890|无论如何，逆转换是可以精确完成的。|3889891|extension+String+{
++++///+O(1)+if+`self`+is+optimised+to+use+UTF-16.
++++///+O(n)+otherwise.
++++public+func+convertRangeToNSRange(r:Range<String.Index>)+->+NSRange+{
++++++++let+a+++=+++substringToIndex(r.startIndex)
++++++++let+b+++=+++substringWithRange(r)

++++++++return++NSRange(location:+a.utf16Count,+length:+b.utf16Count)
++++}
}
println(convertRangeToNSRange(s.startIndex..<s.endIndex))
println(convertRangeToNSRange(s.startIndex.successor()..<s.endIndex))|3889892|3889893|(0,6)
(4,2)|3889894|entityMap^0|0|0|0|0|0|0|7|9|8|W|J|1N|6|0|2|J|2F|6|0|0|7|F|G|19|C|0|6|C|R|9|1U|7|0|4|C|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1C|8|@]|9|@]|A|$]]|$1|I|3|-4|5|D|7|1D|8|@]|9|@]|A|$E|F]]|$1|J|3|K|5|6|7|1E|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|1F|8|@$N|1G|O|1H|P|Q]|$N|1I|O|1J|P|Q]|$N|1K|O|1L|P|Q]|$N|1M|O|1N|P|Q]]|9|@]|A|$]]|$1|R|3|S|5|6|7|1O|8|@$N|1P|O|1Q|P|Q]|$N|1R|O|1S|P|Q]]|9|@]|A|$]]|$1|T|3|U|5|6|7|1T|8|@$N|1U|O|1V|P|Q]|$N|1W|O|1X|P|Q]|$N|1Y|O|1Z|P|Q]]|9|@]|A|$]]|$1|V|3|W|5|6|7|20|8|@$N|21|O|22|P|Q]|$N|23|O|24|P|Q]|$N|25|O|26|P|Q]]|9|@]|A|$]]|$1|X|3|Y|5|6|7|27|8|@$N|28|O|29|P|Q]]|9|@]|A|$]]|$1|Z|3|10|5|6|7|2A|8|@]|9|@]|A|$]]|$1|11|3|12|5|6|7|2B|8|@]|9|@]|A|$]]|$1|13|3|14|5|D|7|2C|8|@]|9|@]|A|$E|F]]|$1|15|3|H|5|6|7|2D|8|@]|9|@]|A|$]]|$1|16|3|17|5|D|7|2E|8|@]|9|@]|A|$E|F]]|$1|18|3|-4|5|6|7|2F|8|@]|9|@]|A|$]]]|19|$]]

Here's my best effort. But this cannot check or detect wrong input argument.

<pre><code>extension String {
 /// :r: Must correctly select proper UTF-16 code-unit range. Wrong range will produce wrong result.
 public func convertRangeFromNSRange(r:NSRange) -&gt; Range&lt;String.Index&gt; {
 let a = (self as NSString).substringToIndex(r.location)
 let b = (self as NSString).substringWithRange(r)

 let n1 = distance(a.startIndex, a.endIndex)
 let n2 = distance(b.startIndex, b.endIndex)

 let i1 = advance(startIndex, n1)
 let i2 = advance(i1, n2)

 return Range&lt;String.Index&gt;(start: i1, end: i2)
 }
}

let s = ""
println(s[s.convertRangeFromNSRange(NSRange(location: 4, length: 2))]) // Proper range. Produces correct result.
println(s[s.convertRangeFromNSRange(NSRange(location: 0, length: 4))]) // Proper range. Produces correct result.
println(s[s.convertRangeFromNSRange(NSRange(location: 0, length: 2))]) // Improper range. Produces wrong result.
println(s[s.convertRangeFromNSRange(NSRange(location: 0, length: 1))]) // Improper range. Produces wrong result.
</code></pre>

Result.

<pre><code>



</code></pre>

<h2>Details</h2>

<code>NSRange</code> from <code>NSString</code> counts UTF-16 code-units. And <code>Range&lt;String.Index&gt;</code> from Swift <code>String</code> is an opaque relative type which provides only equality and navigation operations. This is intentionally hidden design.

Though the <code>Range&lt;String.Index&gt;</code> seem to be mapped to UTF-16 code-unit offset, that is just an implementation detail, and I couldn't find any mention about any guarantee. That means the implementation details can be changed at any time. Internal representation of Swift <code>String</code> is not pretty defined, and I cannot rely on it.

<code>NSRange</code> values can be directly mapped to <code>String.UTF16View</code> indexes. But there's no method to convert it into <code>String.Index</code>.

Swift <code>String.Index</code> is index to iterate Swift <code>Character</code> which is an Unicode grapheme cluster. Then, you must provide proper <code>NSRange</code> which selects correct grapheme clusters. If you provide wrong range like the above example, it will produce wrong result because proper grapheme cluster range couldn't be figured out. 

If there's a guarantee that the <code>String.Index</code> is UTF-16 code-unit offset, then problem becomes simple. But it is unlikely to happen.

<h2>Inverse conversion</h2>

Anyway the inverse conversion can be done precisely.

<pre><code>extension String {
 /// O(1) if `self` is optimised to use UTF-16.
 /// O(n) otherwise.
 public func convertRangeToNSRange(r:Range&lt;String.Index&gt;) -&gt; NSRange {
 let a = substringToIndex(r.startIndex)
 let b = substringWithRange(r)

 return NSRange(location: a.utf16Count, length: b.utf16Count)
 }
}
println(convertRangeToNSRange(s.startIndex..&lt;s.endIndex))
println(convertRangeToNSRange(s.startIndex.successor()..&lt;s.endIndex))
</code></pre>

Result.

<pre><code>(0,6)
(4,2)
</code></pre>

blocks|key|3592598|text|在Swift+4+(Xcode+9)中，Swift标准库提供了在Swift字符串范围(Range<String.Index>)和NSString范围(NSRange)之间进行转换的方法。示例：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|3592599|let+str+=+"abc"
let+r1+=+str.range(of:+"")!

//+String+range+to+NSRange:
let+n1+=+NSRange(r1,+in:+str)
print((str+as+NSString).substring(with:+n1))+//+

//+NSRange+back+to+String+range:
let+r2+=+Range(n1,+in:+str)!
print(str[r2])+//+|code-block|syntax|javascript|3592600|因此，文本字段委托方法中的文本替换现在可以作为|3592601|func+textField(_+textField:+UITextField,
+++++++++++++++shouldChangeCharactersIn+range:+NSRange,
+++++++++++++++replacementString+string:+String)+->+Bool+{

++++if+let+oldString+=+textField.text+{
++++++++let+newString+=+oldString.replacingCharacters(in:+Range(range,+in:+oldString)!,
++++++++++++++++++++++++++++++++++++++++++++++++++++++with:+string)
++++++++//+...
++++}
++++//+...
}|3592602|3592603|(+Swift+3及更早版本的旧答案：)|3592604|在SWIFT1.2中，String.Index有一个初始化器|3592605|init?(_+utf16Index:+UTF16Index,+within+characters:+String)|3592606|可用于正确地将NSRange转换为Range<String.Index>+(包括所有表情符号、区域指示符或其他扩展的图形素集群)，而无需中间转换为NSString。|3592607|extension+String+{
++++func+rangeFromNSRange(nsRange+:+NSRange)+->+Range<String.Index>?+{
++++++++let+from16+=+advance(utf16.startIndex,+nsRange.location,+utf16.endIndex)
++++++++let+to16+=+advance(from16,+nsRange.length,+utf16.endIndex)
++++++++if+let+from+=+String.Index(from16,+within:+self),
++++++++++++let+to+=+String.Index(to16,+within:+self)+{
++++++++++++++++return+from+..<+to
++++++++}
++++++++return+nil
++++}
}|3592608|此方法返回一个可选字符串范围，因为并非所有的NSRange都对给定的Swift字符串有效。|3592609|然后，可以将UITextFieldDelegate委托方法编写为|3592610|func+textField(textField:+UITextField,+shouldChangeCharactersInRange+range:+NSRange,+replacementString+string:+String)+->+Bool+{

++++if+let+swRange+=+textField.text.rangeFromNSRange(range)+{
++++++++let+newString+=+textField.text.stringByReplacingCharactersInRange(swRange,+withString:+string)
++++++++//+...
++++}
++++return+true
}|3592611|逆变换是|3592612|extension+String+{
++++func+NSRangeFromRange(range+:+Range<String.Index>)+->+NSRange+{
++++++++let+utf16view+=+self.utf16
++++++++let+from+=+String.UTF16View.Index(range.startIndex,+within:+utf16view)+
++++++++let+to+=+String.UTF16View.Index(range.endIndex,+within:+utf16view)
++++++++return+NSMakeRange(from+-+utf16view.startIndex,+to+-+from)
++++}
}|3592613|一个简单的测试：|3592614|let+str+=+"abc"
let+r1+=+str.rangeOfString("")!

//+String+range+to+NSRange:
let+n1+=+str.NSRangeFromRange(r1)
println((str+as+NSString).substringWithRange(n1))+//+

//+NSRange+back+to+String+range:
let+r2+=+str.rangeFromNSRange(n1)!
println(str.substringWithRange(r2))+//+|3592615|Swift+2的更新：|3592616|Swift+2版本的rangeFromNSRange()已经由Serhii在this+answer中提供，为了完整起见，我在这里包括它：|3592617|extension+String+{
++++func+rangeFromNSRange(nsRange+:+NSRange)+->+Range<String.Index>?+{
++++++++let+from16+=+utf16.startIndex.advancedBy(nsRange.location,+limit:+utf16.endIndex)
++++++++let+to16+=+from16.advancedBy(nsRange.length,+limit:+utf16.endIndex)
++++++++if+let+from+=+String.Index(from16,+within:+self),
++++++++++++let+to+=+String.Index(to16,+within:+self)+{
++++++++++++++++return+from+..<+to
++++++++}
++++++++return+nil
++++}
}|3592618|Swift+2版本的NSRangeFromRange()是|3592619|extension+String+{
++++func+NSRangeFromRange(range+:+Range<String.Index>)+->+NSRange+{
++++++++let+utf16view+=+self.utf16
++++++++let+from+=+String.UTF16View.Index(range.startIndex,+within:+utf16view)
++++++++let+to+=+String.UTF16View.Index(range.endIndex,+within:+utf16view)
++++++++return+NSMakeRange(utf16view.startIndex.distanceTo(from),+from.distanceTo(to))
++++}
}|3592620|Swift+3的更新(Xcode+8):|3592621|extension+String+{
++++func+nsRange(from+range:+Range<String.Index>)+->+NSRange+{
++++++++let+from+=+range.lowerBound.samePosition(in:+utf16)
++++++++let+to+=+range.upperBound.samePosition(in:+utf16)
++++++++return+NSRange(location:+utf16.distance(from:+utf16.startIndex,+to:+from),
+++++++++++++++++++++++length:+utf16.distance(from:+from,+to:+to))
++++}
}

extension+String+{
++++func+range(from+nsRange:+NSRange)+->+Range<String.Index>?+{
++++++++guard
++++++++++++let+from16+=+utf16.index(utf16.startIndex,+offsetBy:+nsRange.location,+limitedBy:+utf16.endIndex),
++++++++++++let+to16+=+utf16.index(utf16.startIndex,+offsetBy:+nsRange.location+%2B+nsRange.length,+limitedBy:+utf16.endIndex),
++++++++++++let+from+=+from16.samePosition(in:+self),
++++++++++++let+to+=+to16.samePosition(in:+self)
++++++++++++else+{+return+nil+}
++++++++return+from+..<+to
++++}
}|3592622|示例：|3592623|let+str+=+"abc"
let+r1+=+str.range(of:+"")!

//+String+range+to+NSRange:
let+n1+=+str.nsRange(from:+r1)
print((str+as+NSString).substring(with:+n1))+//+

//+NSRange+back+to+String+range:
let+r2+=+str.range(from:+n1)!
print(str.substring(with:+r2))+//+|3592624|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/32379600/1187415^0|1|7|17|J|1S|8|23|7|0|0|0|0|0|0|B|C|0|0|7|7|H|J|21|8|0|0|M|7|0|6|J|0|0|0|0|0|0|8|3|0|A|I|12|B|0|0|0|A|I|0|0|8|C|0|0|0|0^^$0|@$1|2|3|4|5|6|7|24|8|@$9|25|A|26|B|C]|$9|27|A|28|B|D]|$9|29|A|2A|B|D]|$9|2B|A|2C|B|D]]|E|@]|F|$]]|$1|G|3|H|5|I|7|2D|8|@]|E|@]|F|$J|K]]|$1|L|3|M|5|6|7|2E|8|@]|E|@]|F|$]]|$1|N|3|O|5|I|7|2F|8|@]|E|@]|F|$J|K]]|$1|P|3|-4|5|6|7|2G|8|@]|E|@]|F|$]]|$1|Q|3|R|5|6|7|2H|8|@]|E|@]|F|$]]|$1|S|3|T|5|6|7|2I|8|@$9|2J|A|2K|B|D]]|E|@]|F|$]]|$1|U|3|V|5|I|7|2L|8|@]|E|@]|F|$J|K]]|$1|W|3|X|5|6|7|2M|8|@$9|2N|A|2O|B|D]|$9|2P|A|2Q|B|D]|$9|2R|A|2S|B|D]]|E|@]|F|$]]|$1|Y|3|Z|5|I|7|2T|8|@]|E|@]|F|$J|K]]|$1|10|3|11|5|6|7|2U|8|@$9|2V|A|2W|B|D]]|E|@]|F|$]]|$1|12|3|13|5|6|7|2X|8|@$9|2Y|A|2Z|B|D]]|E|@]|F|$]]|$1|14|3|15|5|I|7|30|8|@]|E|@]|F|$J|K]]|$1|16|3|17|5|6|7|31|8|@]|E|@]|F|$]]|$1|18|3|19|5|I|7|32|8|@]|E|@]|F|$J|K]]|$1|1A|3|1B|5|6|7|33|8|@]|E|@]|F|$]]|$1|1C|3|1D|5|I|7|34|8|@]|E|@]|F|$J|K]]|$1|1E|3|1F|5|6|7|35|8|@$9|36|A|37|B|C]]|E|@]|F|$]]|$1|1G|3|1H|5|6|7|38|8|@$9|39|A|3A|B|D]]|E|@$9|3B|A|3C|1|3D]]|F|$]]|$1|1I|3|1J|5|I|7|3E|8|@]|E|@]|F|$J|K]]|$1|1K|3|1L|5|6|7|3F|8|@$9|3G|A|3H|B|D]]|E|@]|F|$]]|$1|1M|3|1N|5|I|7|3I|8|@]|E|@]|F|$J|K]]|$1|1O|3|1P|5|6|7|3J|8|@$9|3K|A|3L|B|C]]|E|@]|F|$]]|$1|1Q|3|1R|5|I|7|3M|8|@]|E|@]|F|$J|K]]|$1|1S|3|1T|5|6|7|3N|8|@]|E|@]|F|$]]|$1|1U|3|1V|5|I|7|3O|8|@]|E|@]|F|$J|K]]|$1|1W|3|-4|5|6|7|3P|8|@]|E|@]|F|$]]]|1X|$1Y|$5|1Z|20|21|F|$22|23]]]]

As of Swift 4 (Xcode 9), the Swift standard
library provides methods to convert between Swift string ranges
(<code>Range&lt;String.Index&gt;</code>) and <code>NSString</code> ranges (<code>NSRange</code>).
Example:

<pre><code>let str = "abc"
let r1 = str.range(of: "")!

// String range to NSRange:
let n1 = NSRange(r1, in: str)
print((str as NSString).substring(with: n1)) // 

// NSRange back to String range:
let r2 = Range(n1, in: str)!
print(str[r2]) // 
</code></pre>

Therefore the text replacement in the text field delegate method
can now be done as

<pre><code>func textField(_ textField: UITextField,
 shouldChangeCharactersIn range: NSRange,
 replacementString string: String) -&gt; Bool {

 if let oldString = textField.text {
 let newString = oldString.replacingCharacters(in: Range(range, in: oldString)!,
 with: string)
 // ...
 }
 // ...
}
</code></pre>

<hr>

(Older answers for Swift 3 and earlier:)

As of Swift 1.2, <code>String.Index</code> has an initializer

<pre><code>init?(_ utf16Index: UTF16Index, within characters: String)
</code></pre>

which can be used to convert <code>NSRange</code> to <code>Range&lt;String.Index&gt;</code> correctly
(including all cases of Emojis, Regional Indicators or other extended
grapheme clusters) without intermediate conversion to an <code>NSString</code>:

<pre><code>extension String {
 func rangeFromNSRange(nsRange : NSRange) -&gt; Range&lt;String.Index&gt;? {
 let from16 = advance(utf16.startIndex, nsRange.location, utf16.endIndex)
 let to16 = advance(from16, nsRange.length, utf16.endIndex)
 if let from = String.Index(from16, within: self),
 let to = String.Index(to16, within: self) {
 return from ..&lt; to
 }
 return nil
 }
}
</code></pre>

This method returns an optional string range because not all <code>NSRange</code>s
are valid for a given Swift string.

The <code>UITextFieldDelegate</code> delegate method can then be written as

<pre><code>func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -&gt; Bool {

 if let swRange = textField.text.rangeFromNSRange(range) {
 let newString = textField.text.stringByReplacingCharactersInRange(swRange, withString: string)
 // ...
 }
 return true
}
</code></pre>

The inverse conversion is

<pre><code>extension String {
 func NSRangeFromRange(range : Range&lt;String.Index&gt;) -&gt; NSRange {
 let utf16view = self.utf16
 let from = String.UTF16View.Index(range.startIndex, within: utf16view) 
 let to = String.UTF16View.Index(range.endIndex, within: utf16view)
 return NSMakeRange(from - utf16view.startIndex, to - from)
 }
}
</code></pre>

A simple test:

<pre><code>let str = "abc"
let r1 = str.rangeOfString("")!

// String range to NSRange:
let n1 = str.NSRangeFromRange(r1)
println((str as NSString).substringWithRange(n1)) // 

// NSRange back to String range:
let r2 = str.rangeFromNSRange(n1)!
println(str.substringWithRange(r2)) // 
</code></pre>

Update for Swift 2:

The Swift 2 version of <code>rangeFromNSRange()</code> was already given 
by Serhii Yakovenko in <a href="https://stackoverflow.com/a/32379600/1187415">this answer</a>, I am including it
here for completeness:

<pre><code>extension String {
 func rangeFromNSRange(nsRange : NSRange) -&gt; Range&lt;String.Index&gt;? {
 let from16 = utf16.startIndex.advancedBy(nsRange.location, limit: utf16.endIndex)
 let to16 = from16.advancedBy(nsRange.length, limit: utf16.endIndex)
 if let from = String.Index(from16, within: self),
 let to = String.Index(to16, within: self) {
 return from ..&lt; to
 }
 return nil
 }
}
</code></pre>

The Swift 2 version of <code>NSRangeFromRange()</code> is

<pre><code>extension String {
 func NSRangeFromRange(range : Range&lt;String.Index&gt;) -&gt; NSRange {
 let utf16view = self.utf16
 let from = String.UTF16View.Index(range.startIndex, within: utf16view)
 let to = String.UTF16View.Index(range.endIndex, within: utf16view)
 return NSMakeRange(utf16view.startIndex.distanceTo(from), from.distanceTo(to))
 }
}
</code></pre>

Update for Swift 3 (Xcode 8):

<pre><code>extension String {
 func nsRange(from range: Range&lt;String.Index&gt;) -&gt; NSRange {
 let from = range.lowerBound.samePosition(in: utf16)
 let to = range.upperBound.samePosition(in: utf16)
 return NSRange(location: utf16.distance(from: utf16.startIndex, to: from),
 length: utf16.distance(from: from, to: to))
 }
}

extension String {
 func range(from nsRange: NSRange) -&gt; Range&lt;String.Index&gt;? {
 guard
 let from16 = utf16.index(utf16.startIndex, offsetBy: nsRange.location, limitedBy: utf16.endIndex),
 let to16 = utf16.index(utf16.startIndex, offsetBy: nsRange.location + nsRange.length, limitedBy: utf16.endIndex),
 let from = from16.samePosition(in: self),
 let to = to16.samePosition(in: self)
 else { return nil }
 return from ..&lt; to
 }
}
</code></pre>

Example:

<pre><code>let str = "abc"
let r1 = str.range(of: "")!

// String range to NSRange:
let n1 = str.nsRange(from: r1)
print((str as NSString).substring(with: n1)) // 

// NSRange back to String range:
let r2 = str.range(from: n1)!
print(str.substring(with: r2)) // 
</code></pre>

blocks|key|3592639|text|我发现最干净的swift2唯一解决方案是在NSRange上创建一个类别：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3592640|extension+NSRange+{
++++func+stringRangeForText(string:+String)+->+Range<String.Index>+{
++++++++let+start+=+string.startIndex.advancedBy(self.location)
++++++++let+end+=+start.advancedBy(self.length)
++++++++return+Range<String.Index>(start:+start,+end:+end)
++++}
}|code-block|syntax|javascript|3592641|然后从text字段委托函数调用它：|3592642|func+textField(textField:+UITextField,+shouldChangeCharactersInRange+range:+NSRange,+replacementString+string:+String)+->+Bool+{
++++let+range+=+range.stringRangeForText(textField.text)
++++let+output+=+textField.text.stringByReplacingCharactersInRange(range,+withString:+string)

++++//+your+code+goes+here....

++++return+true
}|3592643|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I've found the cleanest swift2 only solution is to create a category on NSRange:

<pre><code>extension NSRange {
 func stringRangeForText(string: String) -&gt; Range&lt;String.Index&gt; {
 let start = string.startIndex.advancedBy(self.location)
 let end = start.advancedBy(self.length)
 return Range&lt;String.Index&gt;(start: start, end: end)
 }
}
</code></pre>

And then call it from for text field delegate function:

<pre><code>func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -&gt; Bool {
 let range = range.stringRangeForText(textField.text)
 let output = textField.text.stringByReplacingCharactersInRange(range, withString: string)

 // your code goes here....

 return true
}
</code></pre>

blocks|key|3592652|text|Martin的This+answer似乎是正确的，因为它解释了Unicode。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3592653|然而，在发布文章(Swift+1)时，他的代码没有在SWIFT2.0+(Xcode+7)中编译，因为它们删除了advance()函数。最新版本如下：|style|CODE|3592654|Swift+2|3592655|extension+String+{
++++func+rangeFromNSRange(nsRange+:+NSRange)+->+Range<String.Index>?+{
++++++++let+from16+=+utf16.startIndex.advancedBy(nsRange.location,+limit:+utf16.endIndex)
++++++++let+to16+=+from16.advancedBy(nsRange.length,+limit:+utf16.endIndex)
++++++++if+let+from+=+String.Index(from16,+within:+self),
++++++++++++let+to+=+String.Index(to16,+within:+self)+{
++++++++++++++++return+from+..<+to
++++++++}
++++++++return+nil
++++}
}|code-block|syntax|javascript|3592656|Swift+3|3592657|extension+String+{
++++func+rangeFromNSRange(nsRange+:+NSRange)+->+Range<String.Index>?+{
++++++++if+let+from16+=+utf16.index(utf16.startIndex,+offsetBy:+nsRange.location,+limitedBy:+utf16.endIndex),
++++++++++++let+to16+=+utf16.index(from16,+offsetBy:+nsRange.length,+limitedBy:+utf16.endIndex),
++++++++++++let+from+=+String.Index(from16,+within:+self),
++++++++++++let+to+=+String.Index(to16,+within:+self)+{
++++++++++++++++return+from+..<+to
++++++++}
++++++++return+nil
++++}
}|3592658|Swift+4|3592659|extension+String+{
++++func+rangeFromNSRange(nsRange+:+NSRange)+->+Range<String.Index>?+{
++++++++return+Range(nsRange,+in:+self)
++++}
}|3592660|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/30404532/829739^0|7|B|0|0|1J|9|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@$A|15|B|16|1|17]]|C|$]]|$1|D|3|E|5|6|7|18|8|@$A|19|B|1A|F|G]]|9|@]|C|$]]|$1|H|3|I|5|6|7|1B|8|@]|9|@]|C|$]]|$1|J|3|K|5|L|7|1C|8|@]|9|@]|C|$M|N]]|$1|O|3|P|5|6|7|1D|8|@]|9|@]|C|$]]|$1|Q|3|R|5|L|7|1E|8|@]|9|@]|C|$M|N]]|$1|S|3|T|5|6|7|1F|8|@]|9|@]|C|$]]|$1|U|3|V|5|L|7|1G|8|@]|9|@]|C|$M|N]]|$1|W|3|-4|5|6|7|1H|8|@]|9|@]|C|$]]]|X|$Y|$5|Z|10|11|C|$12|13]]]]

<a href="https://stackoverflow.com/a/30404532/829739">This answer</a> by Martin R seems to be correct because it accounts for Unicode.

However at the time of the post (Swift 1) his code doesn't compile in Swift 2.0 (Xcode 7), because they removed <code>advance()</code> function. Updated version is below:

<h3>Swift 2</h3>

<pre><code>extension String {
 func rangeFromNSRange(nsRange : NSRange) -&gt; Range&lt;String.Index&gt;? {
 let from16 = utf16.startIndex.advancedBy(nsRange.location, limit: utf16.endIndex)
 let to16 = from16.advancedBy(nsRange.length, limit: utf16.endIndex)
 if let from = String.Index(from16, within: self),
 let to = String.Index(to16, within: self) {
 return from ..&lt; to
 }
 return nil
 }
}
</code></pre>

<h3>Swift 3</h3>

<pre><code>extension String {
 func rangeFromNSRange(nsRange : NSRange) -&gt; Range&lt;String.Index&gt;? {
 if let from16 = utf16.index(utf16.startIndex, offsetBy: nsRange.location, limitedBy: utf16.endIndex),
 let to16 = utf16.index(from16, offsetBy: nsRange.length, limitedBy: utf16.endIndex),
 let from = String.Index(from16, within: self),
 let to = String.Index(to16, within: self) {
 return from ..&lt; to
 }
 return nil
 }
}
</code></pre>

<h3>Swift 4</h3>

<pre><code>extension String {
 func rangeFromNSRange(nsRange : NSRange) -&gt; Range&lt;String.Index&gt;? {
 return Range(nsRange, in: self)
 }
}
</code></pre>

blocks|key|4283147|text|在SWIFT2.0中假设func+textField(textField:+UITextField,+shouldChangeCharactersInRange+range:+NSRange,+replacementString+string:+String)+->+Bool+{|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4283148|var+oldString+=+textfield.text!
let+newRange+=+oldString.startIndex.advancedBy(range.location)..<oldString.startIndex.advancedBy(range.location+%2B+range.length)
let+newString+=+oldString.stringByReplacingCharactersInRange(newRange,+withString:+string)|code-block|syntax|javascript|4283149|entityMap^0|C|3K|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

In Swift 2.0 assuming <code>func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -&gt; Bool {</code>:

<pre class="lang-swift prettyprint-override"><code>var oldString = textfield.text!
let newRange = oldString.startIndex.advancedBy(range.location)..&lt;oldString.startIndex.advancedBy(range.location + range.length)
let newString = oldString.stringByReplacingCharactersInRange(newRange, withString: string)
</code></pre>

blocks|key|4283169|text|SWIFT3.0测试版官方文档为这种情况提供了标准解决方案，标题为String.UTF16View+(+UTF16View元素匹配NSString字符标题)|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|4283170|entityMap^0|X|G|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

The Swift 3.0 beta official documentation has provided its standard solution for this situation under the title String.UTF16View in section UTF16View Elements Match NSString Characters title

blocks|key|3592665|text|func+textField(textField:+UITextField,+shouldChangeCharactersInRange+range:+NSRange,+replacementString+string:+String)+->+Bool+{

+++++++let+strString+=+((textField.text)!+as+NSString).stringByReplacingCharactersInRange(range,+withString:+string)

+}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3592666|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -&gt; Bool {

 let strString = ((textField.text)! as NSString).stringByReplacingCharactersInRange(range, withString: string)

 }
</code></pre>

blocks|key|4283172|text|在被接受的答案中，我发现选项很麻烦。这适用于Swift+3，似乎对表情没有任何问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4283173|func+textField(_+textField:+UITextField,+
++++++shouldChangeCharactersIn+range:+NSRange,+
++++++replacementString+string:+String)+->+Bool+{

++guard+let+value+=+textField.text+else+{return+false}+//+there+may+be+a+reason+for+returning+true+in+this+case+but+I+can't+think+of+it
++//+now+value+is+a+String,+not+an+optional+String

++let+valueAfterChange+=+(value+as+NSString).replacingCharacters(in:+range,+with:+string)
++//+valueAfterChange+is+a+String,+not+an+optional+String

++//+now+do+whatever+processing+is+required

++return+true++//+or+false,+as+required
}|code-block|syntax|javascript|4283174|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In the accepted answer I find the optionals cumbersome. This works with Swift 3 and seems to have no problem with emojis. 

<pre><code>func textField(_ textField: UITextField, 
 shouldChangeCharactersIn range: NSRange, 
 replacementString string: String) -&gt; Bool {

 guard let value = textField.text else {return false} // there may be a reason for returning true in this case but I can't think of it
 // now value is a String, not an optional String

 let valueAfterChange = (value as NSString).replacingCharacters(in: range, with: string)
 // valueAfterChange is a String, not an optional String

 // now do whatever processing is required

 return true // or false, as required
}
</code></pre>

blocks|key|3592703|text|extension+StringProtocol+where+Index+==+String.Index+{

++++func+nsRange(of+string:+String)+->+NSRange?+{
++++++++guard+let+range+=+self.range(of:+string)+else+{++return+nil+}
++++++++return+NSRange(range,+in:+self)
++++}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3592704|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>extension StringProtocol where Index == String.Index {

 func nsRange(of string: String) -&gt; NSRange? {
 guard let range = self.range(of: string) else { return nil }
 return NSRange(range, in: self)
 }
}
</code></pre>

blocks|key|4283184|text|func+textField(_+textField:+UITextField,+shouldChangeCharactersIn+range:+NSRange,+replacementString+string:+String)+->+Bool+{
++++
++++guard+let+current+=+textField.text,+let+r+=+Range(range,+in:+current)+else+{
++++++++return+false
++++}
++++
++++let+text+=+current.replacingCharacters(in:+r,+with:+string)
++++//+...
++++return+true
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4283185|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -&gt; Bool {
 
 guard let current = textField.text, let r = Range(range, in: current) else {
 return false
 }
 
 let text = current.replacingCharacters(in: r, with: string)
 // ...
 return true
}
</code></pre>

blocks|key|4283215|text|Swift+5解决方案|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|4283216|主引伸的简短回答|4283217|extension+NSRange+{

++++public+init(range:+Range<String.Index>,+
++++++++++++++++originalText:+String)+{

++++++++self.init(location:+range.lowerBound.utf16Offset(in:+originalText),
++++++++++++++++++length:+range.upperBound.utf16Offset(in:+originalText)+-+range.lowerBound.utf16Offset(in:+originalText))
++++}
}|code-block|syntax|javascript|4283218|对于detailed+answer+check+here|4283219|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/68468499/2740218^0|0|B|0|0|0|2|Q|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|11|8|@]|D|@$9|12|A|13|1|14]]|E|$]]|$1|O|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

Swift 5 Solution
Short answer with main extension
<pre class="lang-swift prettyprint-override"><code>extension NSRange {

 public init(range: Range&lt;String.Index&gt;, 
 originalText: String) {

 self.init(location: range.lowerBound.utf16Offset(in: originalText),
 length: range.upperBound.utf16Offset(in: originalText) - range.lowerBound.utf16Offset(in: originalText))
 }
}
</code></pre>
For <a href="https://stackoverflow.com/a/68468499/2740218">detailed answer check here</a>

blocks|key|3890065|text|因为NSRange，当用于NSString操作时，代表UTF-16单元的位置.然后，转换为String.Index的最短方法是通过String.Index(utf16Offset:+Int,+in:+StringProtocol)初始化器进行初始化。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3890066|let+string+=+"...."
let+nsRange+=+NSRange(....)+//+This+NSRange+belongs+to+`string`+variable.
let+range+=+String.Index(utf16Offset:+nsRange.lowerBound,+in:+string)
++++++++..<+String.Index(utf16Offset:+nsRange.upperBound,+in:+string)|code-block|syntax|javascript|3890067|示例：|3890068|let+string+=+"a-\u{1112}\u{1161}\u{11AB}--\u{E9}\u{20DD}-‼--(العلاجية)-f"
let+rangeOfLeftParenthesis+=+(string+as+NSString).range(of:+"(")
let+rangeOfRightParenthesis+=+(string+as+NSString).range(of:+")")
print("string:+\(string)")
let+lowerBound+=+String.Index.init(utf16Offset:+rangeOfLeftParenthesis.upperBound,+in:+string)
let+upperBound+=+String.Index.init(utf16Offset:+rangeOfRightParenthesis.lowerBound,+in:+string)
let+arabicSentenceRange+=+lowerBound+..<+upperBound+//+Instance+of+`Range<String.Index>`
print("arabicSentenceRange:+\(string[arabicSentenceRange])")|3890069|输出：|3890070|string:+a-한--é⃝-‼--(العلاجية)-f
arabicSentenceRange:+العلاجية|3890071|entityMap^0|2|7|D|8|19|C|1T|1E|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|14|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|15|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|16|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|S|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|T|$]]

Because <code>NSRange</code>, when used in <code>NSString</code> operations, represents positions of the UTF-16 units. Then the shortest way to convert to <code>String.Index</code> is to initialise via <code>String.Index(utf16Offset: Int, in: StringProtocol)</code> initialiser.
<pre class="lang-swift prettyprint-override"><code>let string = &quot;....&quot;
let nsRange = NSRange(....) // This NSRange belongs to `string` variable.
let range = String.Index(utf16Offset: nsRange.lowerBound, in: string)
 ..&lt; String.Index(utf16Offset: nsRange.upperBound, in: string)
</code></pre>
Example:
<pre class="lang-swift prettyprint-override"><code>let string = &quot;a-\u{1112}\u{1161}\u{11AB}--\u{E9}\u{20DD}-‼--(العلاجية)-f&quot;
let rangeOfLeftParenthesis = (string as NSString).range(of: &quot;(&quot;)
let rangeOfRightParenthesis = (string as NSString).range(of: &quot;)&quot;)
print(&quot;string: \(string)&quot;)
let lowerBound = String.Index.init(utf16Offset: rangeOfLeftParenthesis.upperBound, in: string)
let upperBound = String.Index.init(utf16Offset: rangeOfRightParenthesis.lowerBound, in: string)
let arabicSentenceRange = lowerBound ..&lt; upperBound // Instance of `Range&lt;String.Index&gt;`
print(&quot;arabicSentenceRange: \(string[arabicSentenceRange])&quot;)
</code></pre>
Output:
<pre><code>string: a-한--é⃝-‼--(العلاجية)-f
arabicSentenceRange: العلاجية
</code></pre>

How can I convert <code>NSRange</code> to <code>Range&lt;String.Index&gt;</code> in Swift? 

I want to use the following <code>UITextFieldDelegate</code> method:

<pre><code> func textField(textField: UITextField!,
 shouldChangeCharactersInRange range: NSRange,
 replacementString string: String!) -&gt; Bool {

textField.text.stringByReplacingCharactersInRange(???, withString: string)
</code></pre>

<img src="https://i.stack.imgur.com/bs7j6.png" alt="enter image description here">

NSRange to Range<String.Index>

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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如何在Swift中将NSRange转换为Range<String.Index>？我想使用以下UITextFieldDelegate方法： func textField(textField: UITextField!, shouldChangeCharactersInRange range: NSRa...

问NSRange到Range<String.Index>
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