blocks|key|63706|text|我正在用Kirsteins的解决方案复制第一个字符。这将大写第一个字符，而不会看到双精度：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|63707|var+s:+String+=+"hello+world"
s+=+prefix(s,+1).capitalizedString+%2B+suffix(s,+countElements(s)+-+1)|code-block|syntax|javascript|63708|我不知道它的效率是高还是低，我只知道它能给我想要的结果。|63709|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I'm getting the first character duplicated with Kirsteins' solution. This will capitalise the first character, without seeing double:

<pre><code>var s: String = "hello world"
s = prefix(s, 1).capitalizedString + suffix(s, countElements(s) - 1)
</code></pre>

I don't know whether it's more or less efficient, I just know that it gives me the desired result.

blocks|key|4570002|text|下面是我用小步骤完成的方法，它类似于@Kirsteins。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4570003|func+capitalizedPhrase(phrase:String)+->+String+{
++++let+firstCharIndex+=+advance(phrase.startIndex,+1)
++++let+firstChar+=+phrase.substringToIndex(firstCharIndex).uppercaseString
++++let+firstCharRange+=+phrase.startIndex..<firstCharIndex
++++return+phrase.stringByReplacingCharactersInRange(firstCharRange,+withString:+firstChar)
}|code-block|syntax|javascript|4570004|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|$]]

Here's the way I did it in small steps, its similar to @Kirsteins. 

<pre><code>func capitalizedPhrase(phrase:String) -&gt; String {
 let firstCharIndex = advance(phrase.startIndex, 1)
 let firstChar = phrase.substringToIndex(firstCharIndex).uppercaseString
 let firstCharRange = phrase.startIndex..&lt;firstCharIndex
 return phrase.stringByReplacingCharactersInRange(firstCharRange, withString: firstChar)
}
</code></pre>

blocks|key|63757|text|献给莱昂纳多·萨维奥·达布斯：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|63758|我认为大多数用例都是为了获得适当的大小写：|63759|import+Foundation

extension+String+{

++++var+toProper:String+{
++++++++var+result+=+lowercaseString
++++++++result.replaceRange(startIndex...startIndex,+with:+String(self[startIndex]).capitalizedString)
++++++++return+result
++++}
}|code-block|syntax|javascript|63760|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Credits to Leonardo Savio Dabus:

I imagine most use cases is to get Proper Casing:

<pre><code>import Foundation

extension String {

 var toProper:String {
 var result = lowercaseString
 result.replaceRange(startIndex...startIndex, with: String(self[startIndex]).capitalizedString)
 return result
 }
}
</code></pre>

blocks|key|4570044|text|我的解决方案是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4570045|func+firstCharacterUppercaseString(string:+String)+->+String+{
++++var+str+=+string+as+NSString
++++let+firstUppercaseCharacter+=+str.substringToIndex(1).uppercaseString
++++let+firstUppercaseCharacterString+=+str.stringByReplacingCharactersInRange(NSMakeRange(0,+1),+withString:+firstUppercaseCharacter)
++++return+firstUppercaseCharacterString
}|code-block|syntax|javascript|4570046|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|$]]

My solution:

<pre><code>func firstCharacterUppercaseString(string: String) -&gt; String {
 var str = string as NSString
 let firstUppercaseCharacter = str.substringToIndex(1).uppercaseString
 let firstUppercaseCharacterString = str.stringByReplacingCharactersInRange(NSMakeRange(0, 1), withString: firstUppercaseCharacter)
 return firstUppercaseCharacterString
}
</code></pre>

blocks|key|63789|text|结合上面的答案，我写了一个小扩展，将每个单词的第一个字母大写(因为这就是我正在寻找的，并认为其他人可以使用它)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|63790|我谦虚地提出：|63791|extension+String+{
++++var+wordCaps:String+{
++++++++let+listOfWords:[String]+=+self.componentsSeparatedByString("+")
++++++++var+returnString:+String+=+""
++++++++for+word+in+listOfWords+{
++++++++++++if+word+!=+""+{
++++++++++++++++var+capWord+=+word.lowercaseString+as+String
++++++++++++++++capWord.replaceRange(startIndex...startIndex,+with:+String(capWord[capWord.startIndex]).uppercaseString)
++++++++++++++++returnString+=+returnString+%2B+capWord+%2B+"+"
++++++++++++}
++++++++}
++++++++if+returnString.hasSuffix("+")+{
++++++++++++returnString.removeAtIndex(returnString.endIndex.predecessor())
++++++++}
++++++++return+returnString
++++}
}|code-block|syntax|javascript|63792|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Incorporating the answers above, I wrote a small extension that capitalizes the first letter of every word (because that's what I was looking for and figured someone else could use it).

I humbly submit:

<pre><code>extension String {
 var wordCaps:String {
 let listOfWords:[String] = self.componentsSeparatedByString(" ")
 var returnString: String = ""
 for word in listOfWords {
 if word != "" {
 var capWord = word.lowercaseString as String
 capWord.replaceRange(startIndex...startIndex, with: String(capWord[capWord.startIndex]).uppercaseString)
 returnString = returnString + capWord + " "
 }
 }
 if returnString.hasSuffix(" ") {
 returnString.removeAtIndex(returnString.endIndex.predecessor())
 }
 return returnString
 }
}
</code></pre>

blocks|key|4570101|text|func+helperCapitalizeFirstLetter(stringToBeCapd:String)->String{
++++let+capString+=+stringToBeCapd.substringFromIndex(stringToBeCapd.startIndex).capitalizedString
++++return+capString
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4570102|同样，只需传入字符串并返回一个大写的字符串即可。|unstyled|4570103|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>func helperCapitalizeFirstLetter(stringToBeCapd:String)-&gt;String{
 let capString = stringToBeCapd.substringFromIndex(stringToBeCapd.startIndex).capitalizedString
 return capString
}
</code></pre>

Also works just pass your string in and get a capitalized one back.

blocks|key|63808|text|extension+String+{
++++var+lowercased:String+{
++++++++var+result+=+Array<Character>(self.characters);
++++++++if+let+first+=+result.first+{+result[0]+=+Character(String(first).uppercaseString)+}
++++++++return+String(result)
++++}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|63809|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 String {
 var lowercased:String {
 var result = Array&lt;Character&gt;(self.characters);
 if let first = result.first { result[0] = Character(String(first).uppercaseString) }
 return String(result)
 }
}
</code></pre>

blocks|key|4570118|text|将字符串中的第一个字符大写|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4570119|extension+String+{
++++var+capitalizeFirst:+String+{
++++++++if+self.characters.count+==+0+{
++++++++++++return+self

++++++++return+String(self[self.startIndex]).capitalized+%2B+String(self.characters.dropFirst())
++++}
}|code-block|syntax|javascript|4570120|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|$]]

Capitalize the first character in the string

<pre><code>extension String {
 var capitalizeFirst: String {
 if self.characters.count == 0 {
 return self

 return String(self[self.startIndex]).capitalized + String(self.characters.dropFirst())
 }
}
</code></pre>

blocks|key|4570135|text|Swift+3+(xcode+8.3.3)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4570136|字符串的前几个字符全部大写|4570137|let+str+=+"your+string"
let+capStr+=+str.capitalized

//Your+String|code-block|syntax|javascript|4570138|全部字符大写|4570139|let+str+=+"your+string"
let+upStr+=+str.uppercased()

//YOUR+STRING|4570140|仅大写字符串的第一个字符|4570141|+var+str+=+"your+string"
+let+capStr+=+String(str.characters.prefix(1)).uppercased()+%2B+String(str.characters.dropFirst())

//Your+string|4570142|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

Swift 3 (xcode 8.3.3)

Uppercase all first characters of string

<pre><code>let str = "your string"
let capStr = str.capitalized

//Your String
</code></pre>

Uppercase all characters

<pre><code>let str = "your string"
let upStr = str.uppercased()

//YOUR STRING
</code></pre>

Uppercase only first character of string

<pre><code> var str = "your string"
 let capStr = String(str.characters.prefix(1)).uppercased() + String(str.characters.dropFirst())

//Your string
</code></pre>

blocks|key|63891|text|我偏向于这个版本，它是来自另一个答案的清理版本：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|63892|extension+String+{
++var+capitalizedFirst:+String+{
++++let+characters+=+self.characters
++++if+let+first+=+characters.first+{
++++++return+String(first).uppercased()+%2B+
+++++++++++++String(characters.dropFirst())
++++}
++++return+self
++}
}|code-block|syntax|javascript|63893|它努力提高效率，只对self.characters求值一次，然后使用一致的形式创建子字符串。|63894|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I'm partial to this version, which is a cleaned up version from another answer:

<pre><code>extension String {
 var capitalizedFirst: String {
 let characters = self.characters
 if let first = characters.first {
 return String(first).uppercased() + 
 String(characters.dropFirst())
 }
 return self
 }
}
</code></pre>

It strives to be more efficient by only evaluating self.characters once, and then uses consistent forms to create the sub-strings.

blocks|key|4570194|text|Swift+4+(Xcode+9.1)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4570195|extension+String+{
++++var+capEachWord:+String+{
++++++++return+self.split(separator:+"+").map+{+word+in
++++++++++++return+String([word.startIndex]).uppercased()+%2B+word.lowercased().dropFirst()
++++++++}.joined(separator:+"+")
++++}
}|code-block|syntax|javascript|4570196|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|$]]

Swift 4 (Xcode 9.1)

<pre><code>extension String {
 var capEachWord: String {
 return self.split(separator: " ").map { word in
 return String([word.startIndex]).uppercased() + word.lowercased().dropFirst()
 }.joined(separator: " ")
 }
}
</code></pre>

blocks|key|4570213|text|对于word中的第一个字符，请使用swift中的.capitalized；对于整个单词，请使用.uppercased()|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4570214|entityMap^0|O|C|1B|D|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

For first character in word use <code>.capitalized</code> in swift and for whole-word use <code>.uppercased()</code>

blocks|key|63959|text|如果你的字符串都是大写的，那么下面的方法将起作用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|63960|labelTitle.text+=+remarks?.lowercased().firstUppercased|code-block|syntax|javascript|63961|此扩展将帮助您|63962|extension+StringProtocol+{
++++var+firstUppercased:+String+{
++++++++guard+let+first+=+first+else+{+return+""+}
++++++++return+String(first).uppercased()+%2B+dropFirst()
++++}
}|63963|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|$]]

If your string is all caps then below method will work

<pre><code>labelTitle.text = remarks?.lowercased().firstUppercased
</code></pre>

This extension will helps you

<pre><code>extension StringProtocol {
 var firstUppercased: String {
 guard let first = first else { return "" }
 return String(first).uppercased() + dropFirst()
 }
}
</code></pre>

blocks|key|4570267|text|Swift+4|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4570268|func+firstCharacterUpperCase()+->+String+{
++++++++if+self.count+==+0+{+return+self+}
++++++++return+prefix(1).uppercased()+%2B+dropFirst().lowercased()
++++}|code-block|syntax|javascript|4570269|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|$]]

Swift 4

<pre><code>func firstCharacterUpperCase() -&gt; String {
 if self.count == 0 { return self }
 return prefix(1).uppercased() + dropFirst().lowercased()
 }
</code></pre>

blocks|key|4570275|text|在Swift+3中，您可以轻松使用textField.autocapitalizationType+=+UITextAutocapitalizationType.sentences|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4570276|entityMap^0|H|21|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|$]]

From Swift 3 you can easily use 
<code>textField.autocapitalizationType = UITextAutocapitalizationType.sentences</code>

blocks|key|4570327|text|在swift+5中|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4570328|https://www.hackingwithswift.com/example-code/strings/how-to-capitalize-the-first-letter-of-a-string|offset|length|4570329|extension+String+{
++++func+capitalizingFirstLetter()+->+String+{
++++++++return+prefix(1).capitalized+%2B+dropFirst()
++++}

++++mutating+func+capitalizeFirstLetter()+{
++++++++self+=+self.capitalizingFirstLetter()
++++}
}|code-block|syntax|javascript|4570330|与字符串一起使用|4570331|let+test+=+"the+rain+in+Spain"
print(test.capitalizingFirstLetter())|4570332|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|2S|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|W|8|@]|9|@$D|X|E|Y|1|Z]]|A|$]]|$1|F|3|G|5|H|7|10|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|11|8|@]|9|@]|A|$]]|$1|M|3|N|5|H|7|12|8|@]|9|@]|A|$I|J]]|$1|O|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|C]]]]

In swift 5

<a href="https://www.hackingwithswift.com/example-code/strings/how-to-capitalize-the-first-letter-of-a-string" rel="noreferrer">https://www.hackingwithswift.com/example-code/strings/how-to-capitalize-the-first-letter-of-a-string</a>

<pre><code>extension String {
 func capitalizingFirstLetter() -&gt; String {
 return prefix(1).capitalized + dropFirst()
 }

 mutating func capitalizeFirstLetter() {
 self = self.capitalizingFirstLetter()
 }
}
</code></pre>

use with your string 

<pre><code>let test = "the rain in Spain"
print(test.capitalizingFirstLetter())
</code></pre>

blocks|key|64086|text|对于swift+5，你可以简单地这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|64087|为字符串创建扩展名：|64088|extension+String+{
++++var+firstUppercased:+String+{
++++++++let+firstChar+=+self.first?.uppercased()+??+""
++++++++return+firstChar+%2B+self.dropFirst()
++++}
}|code-block|syntax|javascript|64089|然后|64090|yourString.firstUppercased|64091|示例："abc“->+"Abc”|64092|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

For swift 5, you can simple do like that:
Create extension for String:
<pre><code>extension String {
 var firstUppercased: String {
 let firstChar = self.first?.uppercased() ?? &quot;&quot;
 return firstChar + self.dropFirst()
 }
}
</code></pre>
then
<pre><code>yourString.firstUppercased
</code></pre>
Sample: &quot;abc&quot; -&gt; &quot;Abc&quot;

blocks|key|64119|text|在viewDidLoad()方法中添加这一行。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|64120|+txtFieldName.autocapitalizationType+=+UITextAutocapitalizationType.words|code-block|syntax|javascript|64121|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|$]]

Add this line in viewDidLoad() method. 

<pre><code> txtFieldName.autocapitalizationType = UITextAutocapitalizationType.words
</code></pre>

blocks|key|4570462|text|编辑:这不再适用于文本，现在只支持输入域。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4570463|以防有人在这里结束时提出关于SwiftUI的相同问题：|4570464|//+Mystring+is+here
TextField("mystring+is+here")
+++.autocapitalization(.sentences)


//+Mystring+Is+Here
Text("mystring+is+here")
+++.autocapitalization(.words)|code-block|syntax|javascript|4570465|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Edit: This no longer works with Text, only supports input fields now.
Just in case someone ends here with the same question regarding SwiftUI:
<pre><code>// Mystring is here
TextField(&quot;mystring is here&quot;)
 .autocapitalization(.sentences)


// Mystring Is Here
Text(&quot;mystring is here&quot;)
 .autocapitalization(.words)
</code></pre>

I am trying to make an autocorrect system, and when a user types a word with a capital letter, the autocorrect doesn't work. In order to fix this, I made a copy of the string typed, applied .lowercaseString, and then compared them. If the string is indeed mistyped, it should correct the word. However then the word that replaces the typed word is all lowercase. So I need to apply .uppercaseString to only the first letter. I originally thought I could use

<pre><code>nameOfString[0]
</code></pre>

but this apparently does not work. How can I get the first letter of the string to uppercase, and then be able to print the full string with the first letter capitalized? 

Thanks for any help!

Swift apply .uppercaseString to only the first letter of a string

Swift

Xcode

我正在尝试制作一个自动更正系统，当用户键入一个包含大写字母的单词时，自动更正不起作用。为了解决这个问题，我复制了输入的字符串，应用.lowercaseString，然后对它们进行比较。如果字符串确实打错了，它应该纠正这个单词。然而，替换键入的单词的单词都是小写的。因此，我只需要将.uppercaseString应用于第...

问Swift仅将.uppercaseString应用于字符串的第一个字母
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问Swift仅将.uppercaseString应用于字符串的第一个字母
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