How to achieve that placeholder text disappears character by character in UITextField

Question

Can you please help me.

In UITextField when we provide a placeholder text its placeholder string will be gone when we enter any character. How can I achieve

Answer 1

There is my solution using UITextField text property

+(BOOL)shouldChangeCharactersInRange:(NSRange)range
                   replacementString:(NSString *)string
                           textField:(UITextField *)textField
                                mask:(NSString *)mask withMaskTemplate:(NSString *)maskTemplate{

    NSString * alreadyExistString = @"";
    if (string.length == 0) {
        alreadyExistString = textField.text;
        for (int i = range.location; i >= 0; i--) {
            unichar  currentCharMask = [maskTemplate characterAtIndex:i];
            unichar  currentChar = [alreadyExistString characterAtIndex:i];
            if (currentCharMask == currentChar) {// fixed value and _
                continue;
            }else{
                alreadyExistString = [alreadyExistString stringByReplacingCharactersInRange:NSMakeRange(i, 1) withString:@"_"];
                break;
            }
        }
        textField.text = alreadyExistString;
        return NO;
    }else{
        alreadyExistString = [textField.text stringByReplacingCharactersInRange:NSMakeRange(range.location, 1) withString:string];
    }

    NSMutableString * validText = [[NSMutableString alloc] init];

    int last = 0;
    BOOL append = NO;
    for (int i = 0; i < alreadyExistString.length; i++) {
        unichar  currentCharMask = [mask characterAtIndex:i];
        unichar  currentChar = [alreadyExistString characterAtIndex:i];
        BOOL isLetter = [[NSCharacterSet alphanumericCharacterSet] characterIsMember: currentChar];
        BOOL isDigit  = [[NSCharacterSet decimalDigitCharacterSet] characterIsMember: currentChar];
        if ((isLetter && currentCharMask == '#') || (isDigit && currentCharMask == '9')) {
            [validText appendString:[NSString stringWithFormat:@"%c",currentChar]];
        }else{
            if (currentCharMask == '#' || currentCharMask == '9') {
                break;
            }
            if ((isLetter && currentCharMask!= currentChar)|| (isDigit && currentCharMask!= currentChar)) {
                append = YES;
            }
            [validText appendString:[NSString stringWithFormat:@"%c",currentCharMask]];
        }
        last = i;
    }

    for (int i = last+1; i < mask.length; i++) {
        unichar currentCharMask = [mask characterAtIndex:i];
        if (currentCharMask != '#' && currentCharMask != '9') {
            [validText appendString:[NSString stringWithFormat:@"%c",currentCharMask]];
        }
        if (currentCharMask == '#' || currentCharMask == '9') {
            break;
        }
    }
    if (append) {
        [validText appendString:string];
    }

    NSString *placeHolderMask = textField.text;
    NSString *sub = [validText substringWithRange:NSMakeRange(range.location, 1)];
    placeHolderMask = [placeHolderMask stringByReplacingCharactersInRange:NSMakeRange(range.location, 1) withString:sub];
    textField.text = placeHolderMask;
    return NO;
}

@property (nonatomic,strong) NSString * maskTemplate;// like: _2_-__-__A
@property (nonatomic,strong) NSString * mask;// like: #2#-99-##A

• Initially set text field text to mask template
• Then when user enters input shouldChangeCharactersInRange invoked and it does a great job

#Edit 1 There is also some more code I have implemented which move the cursor to the underscore location. If someone need help. Please comment I will help you.

#Edit 2

Problems I have facing using this approached

• Not able to change individual text color. The color will be same for both the string like @"_" underscore and input characters has the same color.
• If user not providing any input then I have to provide a check to send blank as a string.
• Tracking for individual inputs.

Thanks, Still waiting for if there is any other workaround using Placeholder String.