NSTimeInterval Formatting

Question

I want to take my NSTimeInterval and format it into a string as 00:00:00 (hours, minutes, seconds). What is the best way to do this?

Answer 1

"Best" is subjective. The simplest way is this:

unsigned int seconds = (unsigned int)round(myTimeInterval);
NSString *string = [NSString stringWithFormat:@"%02u:%02u:%02u",
    seconds / 3600, (seconds / 60) % 60, seconds % 60];

UPDATE

As of iOS 8.0 and Mac OS X 10.10 (Yosemite), you can use NSDateComponentsFormatter if you need a locale-compliant solution. Example:

NSTimeInterval interval = 1234.56;
NSDateComponentsFormatter *formatter = [[NSDateComponentsFormatter alloc] init];
formatter.allowedUnits = NSCalendarUnitHour | NSCalendarUnitMinute |
    NSCalendarUnitSecond;
formatter.zeroFormattingBehavior = NSDateComponentsFormatterZeroFormattingBehaviorPad;
NSString *string = [formatter stringFromTimeInterval:interval];
NSLog(@"%@", string);
// output: 0:20:34

However, I don't see a way to force it to output two digits for the hour, so if that's important to you, you'll need to use a different solution.