Q:

How to make a NSString always use fixed font width

I want to have an NSString in the format "hh:mm:ss" to use exactly the same amount of pixel space as the string "88:88:88". Is that possible?
Now I'm using:
// ... 
NSMutableString * strS = [[NSMutableString alloc] initWithFormat:@"%d", Seconds];
if (Seconds<10){
  [strS insertString:@"0" atIndex:0];
}

// Make the time to show
[ClocklLabel setText:[NSString stringWithFormat:@"%2@:%2@:%2@", strH,strM,strS]];

with no success!

A:

I think you're looking for a monospaced font. Try using Courier for example:
UIFont *courier = [UIFont fontWithName:@"Courier" size:12.0f];
label.font = courier;

If you're trying to create a digital clock display, you could also simply use a separate label for each number and position the labels however you want.

