NSTimeInterval to NSString formatted as NSDate

Tobe wrote:
I already have the time interval as NSTimeInternal. The real problem is how format the time interval like a date into a string.

- (NSString *) formatInterval: (NSTimeInterval) interval
 {
 unsigned long seconds = interval;
 unsigned long minutes = seconds / 60;
 seconds %= 60;
 unsigned long hours = minutes / 60;
 minutes %= 60;
 NSMutableString * result = [[NSMutableString new] autorelease];
 if(hours)
 [result appendFormat: @"%d:", hours];
 [result appendFormat: @"%02:", minutes];
 [result appendFormat: @"%02", seconds];
 return result;
 }