How to Change label text color by letter by letter with time interval?

Question

I tried below code:

[NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(myTimerMethod:) userInfo:nil repeats:NO];

-(void)myTimerMethod:(NSTimer*)timer
{

    label.textColor = [UIColor colorWithRed:0.5 green:0.5 blue:0.22 alpha:1.0];

}

but i want like below image type to change color.

Answer 1

UILabel now supports attributed string. So you can do something similar to following

int lengthOfTextToColor = 0;
NSMutableAttributedString *textString = [[NSMutableAttributedString alloc] initWithString:@"I think you are making a karaoke app"];

-(void)colorChangeTimer:(NSTimer *)timer {
    lengthOfTextToColor ++;
    NSRange range = NSMakeRange(0, lengthOfTextToColor);
    NSDictionary *colorAttribute = @{NSForegroundColorAttributeName:[UIColor blueColor]};
    [textString setAttributes: colorAttribute range:range];
    self.label.attributedText = textString;
}

But attributed string has its limitations. If you are looking to implement really fancy text, pull up your socks and check Text Programming Guide and CoreText Framework. You can find many tutorials for Core Text

Answer 2

You have to use NSMutableAttributedString:

_string = [[NSMutableAttributedString alloc] initWithString:@"your string"];
_index = 0;
[NSTimer scheduledTimerWithInterval:1.0 target:self selector:@selector(yourSelector) userInfo:nil repeats:NO];

- (void)yourSelector {
    [_string setAttributes:@{NSForegroundColorAttributeName: [UIColor colorWithRed:0 green:0 blue:0 alpha:1]} range:NSMakeRange(_index, 1)];
    [label setAttributedText:_string];
    _index++;
}