iOS 限制textField输入的长度

1.电话号码（带3-3-4效果）

1. //指定代理
     

    self.phoneTextField.delegate = self;

2. 
    
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   1 2	//当编辑改变的时候，进行字符校验  [self.phoneTextField addTarget:self action:@selector(reformatAsPhoneNumber:) forControlEvents:UIControlEventEditingChanged];

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   #pragma mark - 手机号码分隔 /**  *  3-3-4手机号码分隔  */ -(void)reformatAsPhoneNumber:(UITextField *)textField {     //判断正确的光标位置     NSUInteger targetCursorPostion = [textField offsetFromPosition:textField.beginningOfDocument toPosition:textField.selectedTextRange.start];     NSString *phoneNumberWithoutSpaces = [self removeNonDigits:textField.text andPreserveCursorPosition:&targetCursorPostion];     if([phoneNumberWithoutSpaces length] > 11) {         //避免超过11位的输入         [textField setText:_previousTextFieldContent];         textField.selectedTextRange = _previousSelection;         return;     }       NSString *phoneNumberWithSpaces = [self insertSpacesEveryFourDigitsIntoString:phoneNumberWithoutSpaces andPreserveCursorPosition:&targetCursorPostion];       textField.text = phoneNumberWithSpaces;     UITextPosition *targetPostion = [textField positionFromPosition:textField.beginningOfDocument offset:targetCursorPostion];     [textField setSelectedTextRange:[textField textRangeFromPosition:targetPostion toPosition:targetPostion]]; }   /**  *  除去非数字字符，确定光标正确位置  *  *  @param string         当前的string  *  @param cursorPosition 光标位置  *  *  @return 处理过后的string  */ - (NSString *)removeNonDigits:(NSString *)string andPreserveCursorPosition:(NSUInteger *)cursorPosition {     NSUInteger originalCursorPosition = *cursorPosition;     NSMutableString *digitsOnlyString = [NSMutableString new];       for (NSUInteger i=0; i<string.length; i++) {         unichar characterToAdd = [string characterAtIndex:i];           if(isdigit(characterToAdd)) {             NSString *stringToAdd = [NSString stringWithCharacters:&characterToAdd length:1];             [digitsOnlyString appendString:stringToAdd];         }         else {             if(i<originalCursorPosition) {                 (*cursorPosition)--;             }         }     }     return digitsOnlyString; }   /**  *  将空格插入我们现在的string 中，并确定我们光标的正确位置，防止在空格中  *  *  @param string         当前的string  *  @param cursorPosition 光标位置  *  *  @return 处理后有空格的string  */ - (NSString *)insertSpacesEveryFourDigitsIntoString:(NSString *)string andPreserveCursorPosition:(NSUInteger *)cursorPosition{     NSMutableString *stringWithAddedSpaces = [NSMutableString new];     NSUInteger cursorPositionInSpacelessString = *cursorPosition;       for (NSUInteger i=0; i<string.length; i++) {         if(i>0){             if(i==3 || i==7) {                 [stringWithAddedSpaces appendString:@" "];                 if(i<cursorPositionInSpacelessString) {                     (*cursorPosition)++;                 }             }         }         unichar characterToAdd = [string characterAtIndex:i];         NSString *stringToAdd = [NSString stringWithCharacters:&characterToAdd length:1];         [stringWithAddedSpaces appendString:stringToAdd];     }     return stringWithAddedSpaces; }   #pragma mark - UITextFieldDelegate   -(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {     _previousSelection = textField.selectedTextRange;     _previousTextFieldContent = textField.text;     if ( textField == self.phoneHMDTextField &&range.location >= 11){         return  NO;     }else {         return YES;     } }

    

二：监听代理方法（这样可以在if里通过判断，做几个textfield的限制输入）

 

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-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {       if ( textField == self.phoneHMDTextField  && range.location >= 11){         return  NO;     }else {         return YES;     } }

 

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//指定代理       self.phoneTextField.delegate = self;       //当编辑改变的时候，进行字符校验       [self.phoneTextField addTarget:self action:@selector(reformatAsPhoneNumber:) forControlEvents:UIControlEventEditingChanged];   //监听字符改变的方法   - (void)textFieldDidChange:(UITextField *)textField {     if (textField == self.textFieldName) {         if (textField.text.length > 15) { 　　　　　　　　UITextRange *markedRange = [textField markedTextRange];         　　　if (markedRange) {            　　 return;        　　　 }             //Emoji占2个字符，如果是超出了半个Emoji，用15位置来截取会出现Emoji截为2半         //超出最大长度的那个字符序列(Emoji算一个字符序列)的range         NSRange range = [textField.text rangeOfComposedCharacterSequenceAtIndex:15];             textField.text = [textField.text substringToIndex:range.location];         }     } }