iOS *格式化，344格式

@interface ViewController ()<UITextFieldDelegate>
{
    NSString    *previousTextFieldContent;
    UITextRange *previousSelection;
}
@end

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self.textField.delegate = self;
    [self.textField addTarget:self action:@selector(formatPhoneNumber:) forControlEvents:UIControlEventEditingChanged];
}

- (void)formatPhoneNumber:(UITextField*)textField
{
    NSUInteger targetCursorPosition =
    [textField offsetFromPosition:textField.beginningOfDocument
                       toPosition:textField.selectedTextRange.start];
    NSLog(@"targetCursorPosition:%li", (long)targetCursorPosition);
    // nStr表示不带空格的号码
    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;
    }
    
    // textField设置text
    if (nStr.length > 11)
    {
        textField.text = previousTextFieldContent;
        textField.selectedTextRange = previousSelection;
        return;
    }
    
    // 空格
    NSString* spaceStr = @" ";
    
    NSMutableString* mStrTemp = [NSMutableString new];
    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];
        }else if (i == 2)
        {
            [mStrTemp appendFormat:@"%@%@", [nStr substringWithRange:NSMakeRange(7, 4)], spaceStr];
        }
    }
    
    if (nStr.length == 11)
    {
        [mStrTemp appendFormat:@"%@%@", [nStr substringWithRange:NSMakeRange(7, 4)], spaceStr];
    }
    
    if (nStr.length < 4)
    {
        [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;
    // 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]];
}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    previousTextFieldContent = textField.text;
    previousSelection = textField.selectedTextRange;
    
    return YES;
}