I try to assign attributes to 3 last chars of newClock string, which is @"3:33:23".
However I get an error when construct NSRange:
NSMutableAttributedString *mas = [[NSMutableAttributedString alloc]initWithString:newClock];
[mas addAttributes:@{NSForegroundColorAttributeName:[UIColor grayColor],
NSFontAttributeName:[UIFont fontWithName:@"HelveticaNeue-Light" size:12]}
range:NSMakeRange(newClock.length-3,newClock.length)];