blocks|key|818538|text|在您从中获得这些值的任何UITextField中，您都可以指定当有人在文本字段内触摸时要显示的键盘类型。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|818539|例如纯数字键盘。|818540|类似以下屏幕截图的：|offset|length|style|BOLD|818541|​|818542|📷|atomic|818543|818544|在使用XIB和Xcode内置的Interface+Builder时，这很容易设置，但如果您想通过编程来理解这一点，请看一下苹果的UITextInputTraits+protocol+reference+page,+specifically+the+keyboardType+property信息。|CODE|818545|要过滤掉标点符号，请设置文本字段的委托并设置shouldChangeCharactersInRange方法：|818546|-+(BOOL)textField:(UITextField+*)textField+shouldChangeCharactersInRange:(NSRange)range+replacementString:(NSString+*)string
{
 + +NSCharacterSet+*numbersOnly+=+[NSCharacterSet+characterSetWithCharactersInString:@"0123456789"];
++++NSCharacterSet+*characterSetFromTextField+=+[NSCharacterSet+characterSetWithCharactersInString:textField.text];

 + +BOOL+stringIsValid+=+[numbersOnly+isSupersetOfSet:characterSetFromTextField];
 + +return+stringIsValid;
}|code-block|syntax|javascript|818547|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/446eddcd6d98623044cf723c216f08e0.jpeg|imageAlt|1|LINK|MUTABLE|url|https://developer.apple.com/library/ios/#documentation/UIKit/Reference/UITextInputTraits_Protocol/Reference/UITextInputTraits.html#//apple_ref/occ/intf/UITextInputTraits^0|0|0|9|1|0|0|0|1|0|0|0|1S|H|3G|C|1S|29|1|0|0|0^^$0|@$1|2|3|4|5|6|7|1D|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1E|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1F|8|@$F|1G|G|1H|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|1I|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|1J|8|@]|9|@$F|1K|G|1L|1|1M]]|A|$]]|$1|O|3|K|5|6|7|1N|8|@]|9|@]|A|$]]|$1|P|3|Q|5|6|7|1O|8|@$F|1P|G|1Q|H|R]|$F|1R|G|1S|H|R]]|9|@$F|1T|G|1U|1|1V]]|A|$]]|$1|S|3|T|5|6|7|1W|8|@]|9|@]|A|$]]|$1|U|3|V|5|W|7|1X|8|@]|9|@]|A|$X|Y]]|$1|Z|3|-4|5|6|7|1Y|8|@]|9|@]|A|$]]]|10|$11|$5|12|13|14|A|$15|16|17|-4]]|18|$5|19|13|1A|A|$1B|1C]]]]

In whatever UITextField you're getting these values from, you can specify the kind of keyboard you want to appear when somebody touches inside the text field.

E.G. a numeric-only keyboard.

Like this screenshot:

<img src="https://i.stack.imgur.com/SyakX.jpg" alt="numeric only keyboard will appear">

This is easily set when working with the XIB and the Interface Builder built into Xcode, but if you want to understand this programmatically, take a look at Apple's <a href="https://developer.apple.com/library/ios/#documentation/UIKit/Reference/UITextInputTraits_Protocol/Reference/UITextInputTraits.html#//apple_ref/occ/intf/UITextInputTraits" rel="noreferrer"><code>UITextInputTraits</code> protocol reference page, specifically the <code>keyboardType</code> property</a> information.

To filter out punctuations, set the textfield's delegate and set up the shouldChangeCharactersInRange method:

<pre><code>- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    NSCharacterSet *numbersOnly = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
 NSCharacterSet *characterSetFromTextField = [NSCharacterSet characterSetWithCharactersInString:textField.text];

    BOOL stringIsValid = [numbersOnly isSupersetOfSet:characterSetFromTextField];
    return stringIsValid;
}
</code></pre>

blocks|key|2457130|text|[textField+setKeyboardType:UIKeyboardTypeNumberPad];|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2457131|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>[textField setKeyboardType:UIKeyboardTypeNumberPad];
</code></pre>

blocks|key|1462363|text|这是检查字符串是否仅包含数值的函数|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1462364|%2B(BOOL)+checkforNumeric:(NSString*)+str
{
++++NSString+*strMatchstring=@"\\b([0-9%25_.%2B\\-]%2B)\\b";+
++++NSPredicate+*textpredicate=[NSPredicate+predicateWithFormat:@"SELF+MATCHES+%25@",+strMatchstring];

++++if(![textpredicate+evaluateWithObject:str])
++++{
++++++++//////NSLog(@"Invalid+email+address+found");
++++++++UIAlertView+*objAlert+=+[[UIAlertView+alloc]+initWithTitle:APP_NAME+message:@"please+enter+valid+text."+delegate:nil+cancelButtonTitle:nil+otherButtonTitles:@"Close",nil];
++++++++[objAlert+show];
++++++++[objAlert+release];
++++++++return+FALSE;
++++}
++++return+TRUE;
}|code-block|syntax|javascript|1462365|在提交按钮上选中它。|1462366|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|$]]

this is the function which checks for the String contains Numeric value only

<pre><code>+(BOOL) checkforNumeric:(NSString*) str
{
 NSString *strMatchstring=@"\\b([0-9%_.+\\-]+)\\b"; 
 NSPredicate *textpredicate=[NSPredicate predicateWithFormat:@"SELF MATCHES %@", strMatchstring];

 if(![textpredicate evaluateWithObject:str])
 {
 //////NSLog(@"Invalid email address found");
 UIAlertView *objAlert = [[UIAlertView alloc] initWithTitle:APP_NAME message:@"please enter valid text." delegate:nil cancelButtonTitle:nil otherButtonTitles:@"Close",nil];
 [objAlert show];
 [objAlert release];
 return FALSE;
 }
 return TRUE;
}
</code></pre>

check it on submit button.

blocks|key|2457166|text|Objective+C|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2457167|-+(BOOL)textField:(UITextField+*)textField+shouldChangeCharactersInRange:(NSRange)range+replacementString:(NSString+*)string
{
++++if+(!string.length)+
++++++++return+YES;

++++if+(textField+==+self.tmpTextField)
++++{
++++++++NSString+*newString+=+[textField.text+stringByReplacingCharactersInRange:range+withString:string];
++++++++NSString+*expression+=+@"%5E([0-9]%2B)?(\\.([0-9]{1,2})?)?$";
++++++++NSRegularExpression+*regex+=+[NSRegularExpression+regularExpressionWithPattern:expression+
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++options:NSRegularExpressionCaseInsensitive+
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++error:nil];
++++++++NSUInteger+numberOfMatches+=+[regex+numberOfMatchesInString:newString
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++options:0
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++range:NSMakeRange(0,+[newString+length])];++++++++
++++++++if+(numberOfMatches+==+0)
++++++++++++return+NO;++++++++
++++}
++++return+YES;
}|code-block|syntax|javascript|2457168|Swift+3.0|2457169|func+textField(_+textField:+UITextField,+shouldChangeCharactersIn+range:+NSRange,+replacementString+string:+String)+->+Bool+{
++++if+!string.characters.count+{
++++++++return+true
++++}
++++do+{
++++++++if+textField+==+self.tmpTextField+{
++++++++++++var+newString+=+textField.text.replacingCharacters(inRange:+range,+with:+string)
++++++++++++var+expression+=+"%5E([0-9]%2B)?(\\.([0-9]{1,2})?)?$"
++++++++++++var+regex+=+try+NSRegularExpression(pattern:+expression,+options:+NSRegularExpressionCaseInsensitive)
++++++++++++var+numberOfMatches+=+regex.numberOfMatches(inString:+newString,+options:+[],+range:+NSRange(location:+0,+length:+newString.characters.count))
++++++++++++if+numberOfMatches+==+0+{
++++++++++++++++return+false
++++++++++++}
++++++++}
++++}
++++catch+let+error+{
++++}
++++return+true
}|2457170|entityMap^0|0|B|0|0|0|9|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

Objective C

<pre><code>- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
 if (!string.length) 
 return YES;

 if (textField == self.tmpTextField)
 {
 NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];
 NSString *expression = @"^([0-9]+)?(\\.([0-9]{1,2})?)?$";
 NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:expression 
 options:NSRegularExpressionCaseInsensitive 
 error:nil];
 NSUInteger numberOfMatches = [regex numberOfMatchesInString:newString
 options:0
 range:NSMakeRange(0, [newString length])]; 
 if (numberOfMatches == 0)
 return NO; 
 }
 return YES;
}
</code></pre>

Swift 3.0

<pre><code>func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -&gt; Bool {
 if !string.characters.count {
 return true
 }
 do {
 if textField == self.tmpTextField {
 var newString = textField.text.replacingCharacters(inRange: range, with: string)
 var expression = "^([0-9]+)?(\\.([0-9]{1,2})?)?$"
 var regex = try NSRegularExpression(pattern: expression, options: NSRegularExpressionCaseInsensitive)
 var numberOfMatches = regex.numberOfMatches(inString: newString, options: [], range: NSRange(location: 0, length: newString.characters.count))
 if numberOfMatches == 0 {
 return false
 }
 }
 }
 catch let error {
 }
 return true
}
</code></pre>

blocks|key|818728|text|我已经实现了具有textField特性的代码片段：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|818729|818730|检查valid+decimalnumber的最大允许值。|ordered-list-item|offset|length|style|BOLD|818731|仅检查数字数字。|818732|818733|代码是UITextField委托方法。在使用此代码段之前，您必须具有以下属性：|CODE|818734|818735|self.maxCharacters|818736|self.numeric+//仅限int+characters.|818737|self.decimalNumeric+//仅限数字和".“、”“、”“(适用于特定区域设置，如俄语)。|818738|818739|代码：|818740|-+(BOOL)textField:(UITextField+*)+textField+shouldChangeCharactersInRange:(NSRange)range+replacementString:(NSString+*)string
{
++++if(self.numeric+%7C%7C+self.decimalNumeric)
++++{
++++++++NSString+*fulltext+=+[textField.text+stringByAppendingString:string];
++++++++NSString+*charactersSetString+=+@"0123456789";

++++++++//+For+decimal+keyboard,+allow+"dot"+and+"comma"+characters.
++++++++if(self.decimalNumeric)+{
++++++++++++charactersSetString+=+[charactersSetString+stringByAppendingString:@".,"];
++++++++}

++++++++NSCharacterSet+*numbersOnly+=+[NSCharacterSet+characterSetWithCharactersInString:charactersSetString];
++++++++NSCharacterSet+*characterSetFromTextField+=+[NSCharacterSet+characterSetWithCharactersInString:fulltext];

++++++++//+If+typed+character+is+out+of+Set,+ignore+it.
++++++++BOOL+stringIsValid+=+[numbersOnly+isSupersetOfSet:characterSetFromTextField];
++++++++if(!stringIsValid)+{
++++++++++++return+NO;
++++++++}

++++++++if(self.decimalNumeric)
++++++++{
++++++++++++NSString+*currentText+=+[textField.text+stringByTrimmingCharactersInSet:[NSCharacterSet+whitespaceCharacterSet]];

++++++++++++//+Change+the+","+(appears+in+other+locale+keyboards,+such+as+russian)+key+ot+"."
++++++++++++currentText+=+[currentText+stringByReplacingOccurrencesOfString:@","+withString:@"."];

++++++++++++//+Check+the+statements+of+decimal+value.
++++++++++++if([fulltext+isEqualToString:@"."])+{
++++++++++++++++textField.text+=+@"0.";
++++++++++++++++return+NO;
++++++++++++}

++++++++++++if([fulltext+rangeOfString:@".."].location+!=+NSNotFound)+{
++++++++++++++++textField.text+=+[fulltext+stringByReplacingOccurrencesOfString:@".."+withString:@"."];
++++++++++++++++return+NO;
++++++++++++}

++++++++++++//+If+second+dot+is+typed,+ignore+it.
++++++++++++NSArray+*dots+=+[fulltext+componentsSeparatedByString:@"."];
++++++++++++if(dots.count+>+2)+{
++++++++++++++++textField.text+=+currentText;
++++++++++++++++return+NO;
++++++++++++}

++++++++++++//+If+first+character+is+zero+and+second+character+is+>+0,+replace+first+with+second.+05+=>+5;
++++++++++++if(fulltext.length+==+2)+{
++++++++++++++++if([[fulltext+substringToIndex:1]+isEqualToString:@"0"]+&&+![fulltext+isEqualToString:@"0."])+{
++++++++++++++++++++textField.text+=+[fulltext+substringWithRange:NSMakeRange(1,+1)];
++++++++++++++++++++return+NO;
++++++++++++++++}
++++++++++++}
++++++++}
++++}

++++//+Check+the+max+characters+typed.
++++NSUInteger+oldLength+=+[textField.text+length];
++++NSUInteger+replacementLength+=+[string+length];
++++NSUInteger+rangeLength+=+range.length;

++++NSUInteger+newLength+=+oldLength+-+rangeLength+%2B+replacementLength;
++++BOOL+returnKey+=+[string+rangeOfString:+@"\n"].location+!=+NSNotFound;

++++return+newLength+<=+_maxCharacters+%7C%7C+returnKey;
}|code-block|syntax|javascript|818741|演示：|818742|​|818743|📷|atomic|818744|818745|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/a8054d2aebced7bb4eb0ae8c0003b8cb.gif|imageAlt^0|0|0|2|D|M|6|0|0|8|0|0|0|13|3|B|0|0|0|I|0|I|0|0|W|0|C|0|0|1G|0|J|0|0|0|3|0|0|0|3|0|0|1|0|0|1|0|1|0|0|0|1|0^^$0|@$1|2|3|4|5|6|7|1L|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|1M|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|1N|8|@$F|1O|G|1P|H|I]|$F|1Q|G|1R|H|I]]|9|@]|A|$]]|$1|J|3|K|5|E|7|1S|8|@$F|1T|G|1U|H|I]]|9|@]|A|$]]|$1|L|3|-4|5|6|7|1V|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|1W|8|@$F|1X|G|1Y|H|I]|$F|1Z|G|20|H|O]]|9|@]|A|$]]|$1|P|3|-4|5|6|7|21|8|@]|9|@]|A|$]]|$1|Q|3|R|5|E|7|22|8|@$F|23|G|24|H|I]|$F|25|G|26|H|O]]|9|@]|A|$]]|$1|S|3|T|5|E|7|27|8|@$F|28|G|29|H|I]|$F|2A|G|2B|H|O]]|9|@]|A|$]]|$1|U|3|V|5|E|7|2C|8|@$F|2D|G|2E|H|I]|$F|2F|G|2G|H|O]]|9|@]|A|$]]|$1|W|3|-4|5|6|7|2H|8|@]|9|@]|A|$]]|$1|X|3|Y|5|6|7|2I|8|@$F|2J|G|2K|H|I]]|9|@]|A|$]]|$1|Z|3|10|5|11|7|2L|8|@]|9|@]|A|$12|13]]|$1|14|3|15|5|6|7|2M|8|@$F|2N|G|2O|H|I]]|9|@]|A|$]]|$1|16|3|17|5|6|7|2P|8|@$F|2Q|G|2R|H|I]]|9|@]|A|$]]|$1|18|3|19|5|1A|7|2S|8|@$F|2T|G|2U|H|I]]|9|@$F|2V|G|2W|1|2X]]|A|$]]|$1|1B|3|17|5|6|7|2Y|8|@$F|2Z|G|30|H|I]]|9|@]|A|$]]|$1|1C|3|-4|5|6|7|31|8|@]|9|@]|A|$]]]|1D|$1E|$5|1F|1G|1H|A|$1I|1J|1K|-4]]]]

<h2>I've implemented the snippet which has the features for textField: </h2>

<ol>
<li>Check the maximum allowed characters.</li>
<li>Check the valid decimal number.</li>
<li>Check only numeric numbers.</li>
</ol>

The code is the <code>UITextField</code> delegate method. Before you use this snippet, you must have these properties:

<ol>
<li><code>self.maxCharacters</code></li>
<li><code>self.numeric</code> // Only int characters.</li>
<li><code>self.decimalNumeric</code> // Only numbers and ".", "," (for specific locales, like Russian).</li>
</ol>

<h2>Code:</h2>

<pre><code>- (BOOL)textField:(UITextField *) textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
 if(self.numeric || self.decimalNumeric)
 {
 NSString *fulltext = [textField.text stringByAppendingString:string];
 NSString *charactersSetString = @"0123456789";

 // For decimal keyboard, allow "dot" and "comma" characters.
 if(self.decimalNumeric) {
 charactersSetString = [charactersSetString stringByAppendingString:@".,"];
 }

 NSCharacterSet *numbersOnly = [NSCharacterSet characterSetWithCharactersInString:charactersSetString];
 NSCharacterSet *characterSetFromTextField = [NSCharacterSet characterSetWithCharactersInString:fulltext];

 // If typed character is out of Set, ignore it.
 BOOL stringIsValid = [numbersOnly isSupersetOfSet:characterSetFromTextField];
 if(!stringIsValid) {
 return NO;
 }

 if(self.decimalNumeric)
 {
 NSString *currentText = [textField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

 // Change the "," (appears in other locale keyboards, such as russian) key ot "."
 currentText = [currentText stringByReplacingOccurrencesOfString:@"," withString:@"."];

 // Check the statements of decimal value.
 if([fulltext isEqualToString:@"."]) {
 textField.text = @"0.";
 return NO;
 }

 if([fulltext rangeOfString:@".."].location != NSNotFound) {
 textField.text = [fulltext stringByReplacingOccurrencesOfString:@".." withString:@"."];
 return NO;
 }

 // If second dot is typed, ignore it.
 NSArray *dots = [fulltext componentsSeparatedByString:@"."];
 if(dots.count &gt; 2) {
 textField.text = currentText;
 return NO;
 }

 // If first character is zero and second character is &gt; 0, replace first with second. 05 =&gt; 5;
 if(fulltext.length == 2) {
 if([[fulltext substringToIndex:1] isEqualToString:@"0"] &amp;&amp; ![fulltext isEqualToString:@"0."]) {
 textField.text = [fulltext substringWithRange:NSMakeRange(1, 1)];
 return NO;
 }
 }
 }
 }

 // Check the max characters typed.
 NSUInteger oldLength = [textField.text length];
 NSUInteger replacementLength = [string length];
 NSUInteger rangeLength = range.length;

 NSUInteger newLength = oldLength - rangeLength + replacementLength;
 BOOL returnKey = [string rangeOfString: @"\n"].location != NSNotFound;

 return newLength &lt;= _maxCharacters || returnKey;
}
</code></pre>

<h2>Demo:</h2>

<img src="https://i.stack.imgur.com/rA0YU.gif" alt="enter image description here">

blocks|key|2457317|text|修改了Michael+Dautermann的回答：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2457318|-+(BOOL)textField:(UITextField+*)textField+shouldChangeCharactersInRange:(NSRange)range+replacementString:(NSString+*)string
{
++++if(string.length+>+0)
++++{
++++++++NSCharacterSet+*numbersOnly+=+[NSCharacterSet+characterSetWithCharactersInString:@"0123456789"];
++++++++NSCharacterSet+*characterSetFromTextField+=+[NSCharacterSet+characterSetWithCharactersInString:string];

++++++++BOOL+stringIsValid+=+[numbersOnly+isSupersetOfSet:characterSetFromTextField];
++++++++return+stringIsValid;
++++}
++++return+YES;
}|code-block|syntax|javascript|2457319|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|$]]

Modified Michael Dautermann's answer:

<pre><code>- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
 if(string.length &gt; 0)
 {
 NSCharacterSet *numbersOnly = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
 NSCharacterSet *characterSetFromTextField = [NSCharacterSet characterSetWithCharactersInString:string];

 BOOL stringIsValid = [numbersOnly isSupersetOfSet:characterSetFromTextField];
 return stringIsValid;
 }
 return YES;
}
</code></pre>

blocks|key|1461866|text|我只是修改了Michael的答案，使其更容易实现。只需确保UITextfield的委派设置为自身即可。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1461867|yourTxtField.delegate+=+self;|code-block|syntax|javascript|1461868|此外，将此代码复制并粘贴到您的主文件中。|1461869|-+(BOOL)textField:(UITextField+*)textField+shouldChangeCharactersInRange:(NSRange)range+replacementString:(NSString+*)string++{

++++if+(textField+==+yourTxtField)+{
++++++++NSCharacterSet+*numbersOnly+=+[NSCharacterSet+characterSetWithCharactersInString:@"0123456789"];
++++++++NSCharacterSet+*characterSetFromTextField+=+[NSCharacterSet+characterSetWithCharactersInString:string];

++++++++BOOL+stringIsValid+=+[numbersOnly+isSupersetOfSet:characterSetFromTextField];
++++++++++++return+stringIsValid;
++++++++}else+{
++++++++++++return+YES;
++++++++}
++++}|1461870|如果您想允许使用空格键，只需在CharactersInString末尾放一个空格，就像这样：|1461871|@"0123456789"+->+@"0123456789+"|1461872|此外：|1461873|如果您想限制字符串的长度，只需将if-function替换为以下内容：|1461874|if+(textField+==+yourTxtField)+{
++++++++NSUInteger+newLength+=+[textField.text+length]+%2B+[string+length]+-+range.length;
++++++++NSCharacterSet+*cs+=+[[NSCharacterSet+characterSetWithCharactersInString:@"1234567890"]+invertedSet];
++++++++NSString+*filtered+=+[[string+componentsSeparatedByCharactersInSet:cs]+componentsJoinedByString:@""];
++++++++return+(([string+isEqualToString:filtered])&&(newLength+<=+10));

++++}|1461875|在我的例子中，末尾的"10“表示字符限制。|1461876|干杯！:)|1461877|entityMap^0|T|B|0|0|0|0|F|I|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|18|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|19|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1A|8|@$9|1B|A|1C|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|H|7|1D|8|@]|D|@]|E|$I|J]]|$1|S|3|T|5|6|7|1E|8|@]|D|@]|E|$]]|$1|U|3|V|5|6|7|1F|8|@]|D|@]|E|$]]|$1|W|3|X|5|H|7|1G|8|@]|D|@]|E|$I|J]]|$1|Y|3|Z|5|6|7|1H|8|@]|D|@]|E|$]]|$1|10|3|11|5|6|7|1I|8|@]|D|@]|E|$]]|$1|12|3|-4|5|6|7|1J|8|@]|D|@]|E|$]]]|13|$]]

I just modified the answer of Michael and made it a little bit easier to implement. Just make sure that the delegate of your <code>UITextfield</code> is set to itself.

<pre><code>yourTxtField.delegate = self;
</code></pre>

Furthermore copy &amp; paste this code into your main file. 

<pre><code>- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

 if (textField == yourTxtField) {
 NSCharacterSet *numbersOnly = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
 NSCharacterSet *characterSetFromTextField = [NSCharacterSet characterSetWithCharactersInString:string];

 BOOL stringIsValid = [numbersOnly isSupersetOfSet:characterSetFromTextField];
 return stringIsValid;
 }else {
 return YES;
 }
 }
</code></pre>

If you want to allow the use of the spacebar just put in a blank space at the end of the <code>CharactersInString</code>, just like so:

<pre><code>@"0123456789" -&gt; @"0123456789 "
</code></pre>

<h2>Additionally:</h2>

If you want to restrict the length of the string just replace the if-function with following:

<pre><code>if (textField == yourTxtField) {
 NSUInteger newLength = [textField.text length] + [string length] - range.length;
 NSCharacterSet *cs = [[NSCharacterSet characterSetWithCharactersInString:@"1234567890"] invertedSet];
 NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];
 return (([string isEqualToString:filtered])&amp;&amp;(newLength &lt;= 10));

 }
</code></pre>

In my case the "10" at the end represents the limit of characters. 

Cheers! :)

blocks|key|2541001|text|以下是Swift的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2541002|在viewDidLoad中设置代理：|2541003|_yourTextField.delegate+=+self|code-block|syntax|javascript|2541004|let+_acceptableCharacters+=+"0123456789."

func+textField(textField:+UITextField,+shouldChangeCharactersInRange+range:+NSRange,+replacementString+string:+String)+->+Bool+{

++++if+(string.characters.count+==+0)+{
++++++++return+true
++++}

++++if+(textField+==+self._yourTextField)+{
++++++++let+cs+=+NSCharacterSet(charactersInString:+self._acceptableCharacters)
++++++++let+filtered+=+string.componentsSeparatedByCharactersInSet(cs).filter+{++!$0.isEmpty+}
++++++++let+str+=+filtered.joinWithSeparator("")

++++++++return+(string+!=+str)
++++}

++++return+true
}|2541005|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|F|7|P|8|@]|9|@]|A|$G|H]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Here is Swift solution:

In viewDidLoad set the delegate:


<pre><code>_yourTextField.delegate = self
</code></pre>

<pre><code>let _acceptableCharacters = "0123456789."

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

 if (string.characters.count == 0) {
 return true
 }

 if (textField == self._yourTextField) {
 let cs = NSCharacterSet(charactersInString: self._acceptableCharacters)
 let filtered = string.componentsSeparatedByCharactersInSet(cs).filter { !$0.isEmpty }
 let str = filtered.joinWithSeparator("")

 return (string != str)
 }

 return true
}
</code></pre>

blocks|key|2457401|text|Swift|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2457402|class+ExampleVC:+UIViewController+{

++++let+numbers+=+"0123456789";

++++override+func+viewDidLoad()+{
++++++++super.viewDidLoad()

++++++++let+textfield+=+UITextField(frame:+CGRectMake(20,+100,+300,+44))
++++++++//make+some+customization,+if+you+want
++++++++self.view.addSubview(textfield)

++++++++textfield.delegate+=+self;
++++}
}

extension+ExampleVC:+UITextFieldDelegate+{

++++func+textField(_+textField:+UITextField,+shouldChangeCharactersIn+range:+NSRange,+replacementString+string:+String)+->+Bool+{
++++++++return+string.characters.count+>+0+?+numbers.contains(string)+:+true
++++}
}|code-block|syntax|javascript|2457403|entityMap^0|0|5|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|$]]

Swift

<pre><code>class ExampleVC: UIViewController {

 let numbers = "0123456789";

 override func viewDidLoad() {
 super.viewDidLoad()

 let textfield = UITextField(frame: CGRectMake(20, 100, 300, 44))
 //make some customization, if you want
 self.view.addSubview(textfield)

 textfield.delegate = self;
 }
}

extension ExampleVC: UITextFieldDelegate {

 func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -&gt; Bool {
 return string.characters.count &gt; 0 ? numbers.contains(string) : true
 }
}
</code></pre>

blocks|key|1462535|text|This+answer在Swift+3中抛出了一些错误，以下是有效的答案：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1462536|func+textField(_+textField:+UITextField,+shouldChangeCharactersIn+range:+NSRange,+replacementString+string:+String)+->+Bool+{
++++if+string.characters.count+==+0+{
++++++++return+true
++++}
++++do+{
++++++++if+textField+==+self.numberTextField+{

++++++++++++let+nString+=+textField.text+as+NSString?
++++++++++++let+newString+=+nString?.replacingCharacters(in:+range,+with:+string)
++++++++++++let+expression+=+"%5E([0-9]%2B)?(\\.([0-9]{1,2})?)?$"
++++++++++++let+regex+=+try+NSRegularExpression(pattern:+expression,+options:+.caseInsensitive)
++++++++++++let+numberOfMatches+=+regex.numberOfMatches(in:+newString!+as+String,+options:+[],+range:+NSRange(location:+0,+length:+(newString?.characters.count)!))

++++++++++++if+numberOfMatches+==+0+{
++++++++++++++++return+false
++++++++++++}
++++++++}
++++}
++++catch+let+error+{
++++}
++++return+true
}|code-block|syntax|javascript|1462537|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/22403622/5620628^0|0|B|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

<a href="https://stackoverflow.com/a/22403622/5620628">This answer</a> threw some error in Swift 3, here's the working answer:

<pre><code>func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -&gt; Bool {
 if string.characters.count == 0 {
 return true
 }
 do {
 if textField == self.numberTextField {

 let nString = textField.text as NSString?
 let newString = nString?.replacingCharacters(in: range, with: string)
 let expression = "^([0-9]+)?(\\.([0-9]{1,2})?)?$"
 let regex = try NSRegularExpression(pattern: expression, options: .caseInsensitive)
 let numberOfMatches = regex.numberOfMatches(in: newString! as String, options: [], range: NSRange(location: 0, length: (newString?.characters.count)!))

 if numberOfMatches == 0 {
 return false
 }
 }
 }
 catch let error {
 }
 return true
}
</code></pre>

blocks|key|1461926|text|以下是swift+4的工作示例|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|1461927|public+func+textField(_+textField:+UITextField,+shouldChangeCharactersIn+range:+NSRange,+replacementString+string:+String)+->+Bool
{
++++//+Allow+Backspace
++++if+string.count+==+0+{
++++++++return+true
++++}

++++//+Allow+Only+Valid+Decimal+Numbers
++++if+let+textFieldText+=+textField.text+++{

++++++++let+finalText+=+(textFieldText+as+NSString).replacingCharacters(in:+range,+with:+string)
++++++++if+Double(finalText)+!=+nil+{
++++++++++++return+true
++++++++}
++++}
++++return+false
}|code-block|syntax|javascript|1461928|entityMap^0|3|7|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|$]]

Here is the working example for swift 4

<pre><code>public func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -&gt; Bool
{
 // Allow Backspace
 if string.count == 0 {
 return true
 }

 // Allow Only Valid Decimal Numbers
 if let textFieldText = textField.text {

 let finalText = (textFieldText as NSString).replacingCharacters(in: range, with: string)
 if Double(finalText) != nil {
 return true
 }
 }
 return false
}
</code></pre>

blocks|key|2541140|text|在文本字段中只输入数值的另一种选择是选择相应文本字段的键盘类型属性。附上截图以供参考。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2541141|📷|atomic|offset|length|2541142|​|2541143|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/b309200052f44101e5964c3e62f946c9.png|imageAlt^0|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|S|8|@]|9|@$E|T|F|U|1|V]]|A|$]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|J|$K|$5|L|M|N|A|$O|P|Q|-4]]]]

Another option of entering only numeric values into your text field is by selecting the keyboard type attribute of the corresponding textfield. Attaching the screenshot for reference.<a href="https://i.stack.imgur.com/oaZlb.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oaZlb.png" alt="Number Pad Selection"></a>

blocks|key|819081|text|Swift+4.2+port+of+the+best+answer由@almas+adlibek提供|type|unstyled|depth|inlineStyleRanges|entityRanges|data|819082|一组配置变量：|819083|private+let+kMaxTextLength+=+8
private+let+kZeroDotted+=+"0."
private+let+kZero+=+"0"
private+let+kDoubleDot+=+".."
private+let+kDot+=+"."
private+let+kPeriod+=+","|code-block|syntax|javascript|819084|现在Swift+4转换了部分代码。|819085|+func+textField(_+textField:+UITextField,+shouldChangeCharactersIn+range:+NSRange,+replacementString+string:+String)+->+Bool+{

++++guard+let+oldText+=+textField.text,+let+swiftRange+=+Range(range,+in:+oldText)+else+{
++++++++return+true
++++}

++++let+newText+=+oldText.replacingCharacters(in:+swiftRange,+with:+string)

++++var+currentText+=++textField.text?.trimmingCharacters(in:+CharacterSet.whitespacesAndNewlines)

++++//+Change+the+","+(appears+in+other+locale+keyboards,+such+as+russian)+key+ot+"."
++++currentText+=+currentText?.replacingOccurrences(of:+kPeriod,+with:+kDot)

++++//+Check+the+statements+of+decimal+value.
++++if+(newText+==+kDot)+{
++++++++textField.text+=+kZeroDotted;
++++++++return+false
++++}

++++if+(newText.range(of:+kDoubleDot)+!=+nil)+{
++++++++textField.text+=+newText.replacingOccurrences(of:+kDoubleDot,+with:+kDot);
++++++++return+false
++++}

++++//+If+second+dot+is+typed,+ignore+it.
++++let+dots+=+newText.components(separatedBy:+kDot)
++++if(dots.count+>+2)+{
++++++++textField.text+=+currentText;
++++++++return+false
++++}

++++//+If+first+character+is+zero+and+second+character+is+>+0,+replace+first+with+second.+05+=>+5;
++++if(newText.count+==+2)+{
++++++++if(newText[0...0]+==+kZero+&&+newText+!=+kZeroDotted)+{
++++++++++++textField.text+=+newText[1...1]
++++++++++++return+false
++++++++}
++++}

++++//+Check+the+max+characters+typed.
++++let+oldLength+=+textField.text?.count+??+0
++++let+replacementLength+=+string.count
++++let+rangeLength+=+range.length

++++let+newLength+=+oldLength+-+rangeLength+%2B+replacementLength;
++++let+returnKey+=+string.rangeOfCharacter(from:+CharacterSet.newlines)+!=+nil

++++return+newLength+<=+kMaxTextLength+%7C%7C+returnKey;
}|819086|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Swift 4.2 port of the best answer here by @almas-adlibek

A bunch of configuration variables:

<pre><code>private let kMaxTextLength = 8
private let kZeroDotted = "0."
private let kZero = "0"
private let kDoubleDot = ".."
private let kDot = "."
private let kPeriod = ","
</code></pre>

Now the Swift 4 converted part of the code.

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

 guard let oldText = textField.text, let swiftRange = Range(range, in: oldText) else {
 return true
 }

 let newText = oldText.replacingCharacters(in: swiftRange, with: string)

 var currentText = textField.text?.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)

 // Change the "," (appears in other locale keyboards, such as russian) key ot "."
 currentText = currentText?.replacingOccurrences(of: kPeriod, with: kDot)

 // Check the statements of decimal value.
 if (newText == kDot) {
 textField.text = kZeroDotted;
 return false
 }

 if (newText.range(of: kDoubleDot) != nil) {
 textField.text = newText.replacingOccurrences(of: kDoubleDot, with: kDot);
 return false
 }

 // If second dot is typed, ignore it.
 let dots = newText.components(separatedBy: kDot)
 if(dots.count &gt; 2) {
 textField.text = currentText;
 return false
 }

 // If first character is zero and second character is &gt; 0, replace first with second. 05 =&gt; 5;
 if(newText.count == 2) {
 if(newText[0...0] == kZero &amp;&amp; newText != kZeroDotted) {
 textField.text = newText[1...1]
 return false
 }
 }

 // Check the max characters typed.
 let oldLength = textField.text?.count ?? 0
 let replacementLength = string.count
 let rangeLength = range.length

 let newLength = oldLength - rangeLength + replacementLength;
 let returnKey = string.rangeOfCharacter(from: CharacterSet.newlines) != nil

 return newLength &lt;= kMaxTextLength || returnKey;
}
</code></pre>

blocks|key|1462002|text|swift+4|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|1462003|这只允许数字输入，您还可以设置字符限制|1462004|func+textField(_+textField:+UITextField,+shouldChangeCharactersIn+range:+NSRange,+replacementString+string:+String)+->+Bool+{
++let+aSet+=+NSCharacterSet(charactersIn:"0123456789").inverted
++let+compSepByCharInSet+=+string.components(separatedBy:+aSet)
++let+numberFiltered+=+compSepByCharInSet.joined(separator:+"")

++if+string+==+numberFiltered+{
++++let+currentText+=+textField.text+??+""
++++guard+let+stringRange+=+Range(range,+in:+currentText)+else+{+return+false+}
++++let+updatedText+=+currentText.replacingCharacters(in:+stringRange,+with:+string)
++++return+updatedText.count+<=+10
++}+else+{
++++return+false
++}
}|code-block|syntax|javascript|1462005|entityMap^0|0|7|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|R|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|S|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

swift 4 

This allows only number input and you can also set character limitation

<pre><code>func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -&gt; Bool {
 let aSet = NSCharacterSet(charactersIn:"0123456789").inverted
 let compSepByCharInSet = string.components(separatedBy: aSet)
 let numberFiltered = compSepByCharInSet.joined(separator: "")

 if string == numberFiltered {
 let currentText = textField.text ?? ""
 guard let stringRange = Range(range, in: currentText) else { return false }
 let updatedText = currentText.replacingCharacters(in: stringRange, with: string)
 return updatedText.count &lt;= 10
 } else {
 return false
 }
}
</code></pre>

I have UITexfields i want that it should accept only number other shows alert that enter a numeric value.
I want that motionSicknessTextFiled should only accept number 

<pre><code>NSString*dogswithMotionSickness=motionSicknessTextField.text;
NSString*valueOne=cereniaTextField.text;
NSString*valueTwo=prescriptionTextField.text;
NSString*valueThree=otherMeansTextField.text;
NSString*valueFour=overtheCounterTextField.text;
</code></pre>

UITextField Should accept number only values

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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我有UITexfields，我希望它应该只接受数字其他显示警报，输入一个数字值。我希望motionSicknessTextFiled应该只接受数字NSString*dogswithMotionSickness=motionSicknessTextField.text;NSString*valueOne=cereniaT...

问UITextField应仅接受数字值
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问UITextField应仅接受数字值EN