NSTimeInterval Formatting - objective-c

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

Since iOS 8.0 there is now NSDateComponentsFormatter which has a stringFromTimeInterval: method.
[[NSDateComponentsFormatter new] stringFromTimeInterval:timeInterval];

Answer 2

"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.

Answer 3

NSTimeInterval interval = ...;
NSDate *date = [NSDate dateWithTimeIntervalSince1970:interval];
NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setDateFormat:#"HH:mm:ss"];
[dateFormatter setTimeZone:[NSTimeZone timeZoneWithName:#"UTC"]];
NSString *formattedDate = [dateFormatter stringFromDate:date];
NSLog(#"hh:mm:ss %#", formattedDate);

Answer 4

swift 4.2
extension Date {
static func timestampString(timeInterval: TimeInterval) -> String? {
let formatter = DateComponentsFormatter()
formatter.unitsStyle = .positional
formatter.zeroFormattingBehavior = .pad
formatter.maximumUnitCount = 0
formatter.allowedUnits = [.hour, .minute, .second]
return formatter.string(from: timeInterval)
}
}
Test code:
let hour = 60 * 50 * 32
Date.timestampString(timeInterval: TimeInterval(hour))
// output "26:40:00"
Change unitStyle to get different styles. like formatter.unitsStyle = .abbreviated get
output: "26h 40m 0s"

Answer 5

A Swift version of #Michael Frederick's answer :
let duration: NSTimeInterval = ...
let durationDate = NSDate(timeIntervalSince1970: duration)
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "HH:mm:ss"
dateFormatter.timeZone = NSTimeZone(name: "UTC")
let durationString = dateFormatter.stringFromDate(durationDate)