Convert NSTimeInterval to NSString in iPhone?
NSTimeInterval is just a double type so you can convert it to string using +stringWithFormat: method
NSTimeInterval today = [[NSDate date] timeIntervalSince1970];
NSString *intervalString = [NSString stringWithFormat:@"%f", today];
-(NSString*)formattedDuration:(NSTimeInterval)interval{
NSDateComponentsFormatter *formatter = [[NSDateComponentsFormatter alloc] init];
formatter.allowedUnits = NSCalendarUnitHour | NSCalendarUnitMinute;
formatter.zeroFormattingBehavior = NSDateComponentsFormatterZeroFormattingBehaviorPad;
NSString *string = [formatter stringFromTimeInterval:interval];
NSLog(@"%@", string);
// output: 0:20:34
return string;
}