Converting CMTime To String is wrong value return

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??

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"