Converting CMTime To String is wrong value return

Question

I want CMTime to String an human readable.
So I Found below code.

extension CMTime {

    var durationText:String {
        let totalSeconds = CMTimeGetSeconds(self)
        let hours:Int = Int(totalSeconds / 3600)
        let minutes:Int = Int(totalSeconds.truncatingRemainder(dividingBy: 3600) / 60)
        let seconds:Int = Int(totalSeconds.truncatingRemainder(dividingBy: 60))

        if hours > 0 {
            return String(format: "%i:%02i:%02i", hours, minutes, seconds)
        } else {
            return String(format: "%02i:%02i", minutes, seconds)
        }
    }

}

And I Have 30 second video files. It's CMTime value is 17945.
I expect this durationText 00:30.
But result is 00:29.
And other video files same.
What Should I fix??

Your durationText extension returns `00:30` for me. when I run `CMTime(value: 30, timescale: 1).durationText` — Leo Dabus, Feb 13 '19 at 03:44
Just some notes. You can use CMTime instance property `seconds`. No need to create a variable for that. `let hours = Int(seconds / 3600)`. Btw Swift is a type inferred language. No need to explicitly set the type to Int. — Leo Dabus, Feb 13 '19 at 03:48
`extension CMTime { var hrs: Int { return Int(seconds / 3600) } var mins: Int { return Int(seconds.truncatingRemainder(dividingBy: 3600) / 60) } var secs: Int { return Int(seconds.truncatingRemainder(dividingBy: 60)) } var duration: String { return hrs > 0 ? String(format: "%i:%02i:%02i", hrs, mins, secs) : String(format: "%02i:%02i", mins, secs) } }` `CMTime(value: 30, timescale: 1).duration` ` — Leo Dabus, Feb 13 '19 at 03:58
@LeoDabus I tried CMTime value is 17945. and timescale is 600 — oddK, Feb 13 '19 at 04:19
@LeoDabus I tried your past answer. but It's just print out `0m 29s` — oddK, Feb 13 '19 at 04:40
You video duration is less than 30s. the duration is `29.90833333333333` what would you expect? Round up the result yourself if you need it. `seconds.rounded(.up)` — Leo Dabus, Feb 13 '19 at 04:40
@LeoDabus No...In Xcode, this video file's duration is 30s. and Finder QuickTime Player also 30s. But why In my app 29s??? — oddK, Feb 13 '19 at 04:43
probably better to use the standard `rounded()` which uses `.toNearestOrAwayFromZero` rounding rule. — Leo Dabus, Feb 13 '19 at 04:46
@LeoDabus So much thankyou. I fixed it. You just answer anything. I select your answer. — oddK, Feb 13 '19 at 04:52

Leo Dabus · Accepted Answer · 2019-02-13T05:52:57.963

You need to round your seconds before calculating your time components.

extension CMTime {
    var roundedSeconds: TimeInterval {
        return seconds.rounded()
    }
    var hours:  Int { return Int(roundedSeconds / 3600) }
    var minute: Int { return Int(roundedSeconds.truncatingRemainder(dividingBy: 3600) / 60) }
    var second: Int { return Int(roundedSeconds.truncatingRemainder(dividingBy: 60)) }
    var positionalTime: String {
        return hours > 0 ?
            String(format: "%d:%02d:%02d",
                   hours, minute, second) :
            String(format: "%02d:%02d",
                   minute, second)
    }
}

Testing all the possible edge rounding cases:

CMTime(value: 0, timescale: 600).positionalTime              // "00:00"
CMTime(value: 300, timescale: 600).positionalTime            // "00:01"
CMTime(value: 600, timescale: 600).positionalTime            // "00:01"

CMTime(value: 18000 - 600, timescale: 600).positionalTime      // "00:29"
CMTime(value: 17945, timescale: 600).positionalTime            // "00:30"
CMTime(value: 18000, timescale: 600).positionalTime            // "00:30"
CMTime(value: 18055, timescale: 600).positionalTime            // "00:30"
CMTime(value: 18000 + 600, timescale: 600).positionalTime      // "00:31"


CMTime(value: 2160000 - 600, timescale: 600).positionalTime  // "59:59"
CMTime(value: 2160000 - 300, timescale: 600).positionalTime  // "1:00:00"
CMTime(value: 2160000, timescale: 600).positionalTime        // "1:00:00"

Converting CMTime To String is wrong value return

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