1.创建两个属性

@property (nonatomic, strong) NSString *previousTextFieldContent;
@property (nonatomic, strong) UITextRange *previousSelection;

2.在- (void)viewDidLoad方法中添加下方法

- (void)viewDidLoad {
[self.userNameTextField addTarget:self action:@selector(formatPhoneNumber:) forControlEvents:UIControlEventEditingChanged];
}

3.赋值属性

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
 _previousTextFieldContent = textField.text;
 _previousSelection = textField.selectedTextRange;
}

4.核心方法

- (void)formatPhoneNumber:(UITextField*)textField {
    
    NSUInteger targetCursorPosition = [textField offsetFromPosition:textField.beginningOfDocument toPosition:textField.selectedTextRange.start];//光标位置
    NSLog(@"targetCursorPosition:%li", (long)targetCursorPosition);
    NSString* nStr = [textField.text stringByReplacingOccurrencesOfString:@" " withString:@""];
    NSString* preTxt = [_previousTextFieldContent stringByReplacingOccurrencesOfString:@" " withString:@""];
    char editFlag = 0;// 正在执行删除操作时为0，否则为1
    if (nStr.length <= preTxt.length) {
        editFlag = 0;
    } else {
        
        editFlag = 1;
    }
    if (nStr.length > 11) {
        textField.text = _previousTextFieldContent;
        textField.selectedTextRange = _previousSelection;
        return;
    }
    NSString* spaceStr = @" ";
    NSMutableString *mStrTemp = [NSMutableString string];
    int spaceCount = 0;
    if (nStr.length < 3 && nStr.length > -1) {
        spaceCount = 0;
    }else if (nStr.length < 7&& nStr.length > 2){
        spaceCount = 1;
    }else if (nStr.length < 12&& nStr.length > 6){
        spaceCount = 2;
    }
    for (int i = 0; i < spaceCount; i++){
        if (i == 0) {
            [mStrTemp appendFormat:@"%@%@", [nStr substringWithRange:NSMakeRange(0, 3)],spaceStr];
        }else if (i == 1){
            [mStrTemp appendFormat:@"%@%@", [nStr substringWithRange:NSMakeRange(3, 4)], spaceStr];
        }
    }
    
    if (nStr.length == 11){
        [mStrTemp appendFormat:@"%@%@", [nStr substringWithRange:NSMakeRange(7, 4)], spaceStr];
    }
    NSLog(@"1111111111mstrTemp=%@",mStrTemp);
    if (nStr.length < 4 && nStr.length > 0){
        [mStrTemp appendString:[nStr substringWithRange:NSMakeRange(nStr.length-nStr.length % 3,nStr.length % 3)]];
    }else if(nStr.length > 3){
        NSString *str = [nStr substringFromIndex:3];
        [mStrTemp appendString:[str substringWithRange:NSMakeRange(str.length-str.length % 4,str.length % 4)]];
        if (nStr.length == 11){
            [mStrTemp deleteCharactersInRange:NSMakeRange(13, 1)];
        }
    }
    NSLog(@"=======mstrTemp=%@",mStrTemp);
    textField.text = mStrTemp; //赋值
    // textField设置selectedTextRange
    NSUInteger curTargetCursorPosition = targetCursorPosition;// 当前光标的偏移位置
    if (editFlag == 0){
        //删除
        if (targetCursorPosition == 9 || targetCursorPosition == 4){
            curTargetCursorPosition = targetCursorPosition - 1;
        }
    }
    else {
        //添加
        if (nStr.length == 8 || nStr.length == 3){
            curTargetCursorPosition = targetCursorPosition + 1;
        }
    }
    
    UITextPosition *targetPosition = [textField positionFromPosition:[textField beginningOfDocument] offset:curTargetCursorPosition];
    
    [textField setSelectedTextRange:[textField textRangeFromPosition:targetPosition toPosition :targetPosition]];// 设置光标位置
}

如果想把空格改成其他字符, 可以将下图中箭头所指的位置,更改为该字符即可.

Paste_Image.png