@r3dm4n的回答很棒。然而，我也需要一个小时。以防别人也需要，这里是:

func formatSecondsToString(_ seconds: TimeInterval) -> String {
    if seconds.isNaN {
        return "00:00:00"
    }
    let sec = Int(seconds.truncatingRemainder(dividingBy: 60))
    let min = Int(seconds.truncatingRemainder(dividingBy: 3600) / 60)
    let hour = Int(seconds / 3600)
    return String(format: "%02d:%02d:%02d", hour, min, sec)
}

下面是Swift3中的另一个简单实现。

func seconds2Timestamp(intSeconds:Int)->String {
   let mins:Int = intSeconds/60
   let hours:Int = mins/60
   let secs:Int = intSeconds%60

   let strTimestamp:String = ((hours<10) ? "0" : "") + String(hours) + ":" + ((mins<10) ? "0" : "") + String(mins) + ":" + ((secs<10) ? "0" : "") + String(secs)
   return strTimestamp
}

基于Vadian的回答，我写了一个扩展，它接受Double(其中TimeInterval是类型别名)，并输出一个格式化为时间的字符串。

extension Double {
  func asString(style: DateComponentsFormatter.UnitsStyle) -> String {
    let formatter = DateComponentsFormatter()
    formatter.allowedUnits = [.hour, .minute, .second, .nanosecond]
    formatter.unitsStyle = style
    return formatter.string(from: self) ?? ""
  }
}

这里是各种DateComponentsFormatter。UnitsStyle选项看起来像这样:

10000.asString(style: .positional)  // 2:46:40
10000.asString(style: .abbreviated) // 2h 46m 40s
10000.asString(style: .short)       // 2 hr, 46 min, 40 sec
10000.asString(style: .full)        // 2 hours, 46 minutes, 40 seconds
10000.asString(style: .spellOut)    // two hours, forty-six minutes, forty seconds
10000.asString(style: .brief)       // 2hr 46min 40sec

我已经构建了一个现有答案的mashup，以简化一切并减少Swift 3所需的代码量。

func hmsFrom(seconds: Int, completion: @escaping (_ hours: Int, _ minutes: Int, _ seconds: Int)->()) {

        completion(seconds / 3600, (seconds % 3600) / 60, (seconds % 3600) % 60)

}

func getStringFrom(seconds: Int) -> String {

    return seconds < 10 ? "0\(seconds)" : "\(seconds)"
}

用法:

var seconds: Int = 100

hmsFrom(seconds: seconds) { hours, minutes, seconds in

    let hours = getStringFrom(seconds: hours)
    let minutes = getStringFrom(seconds: minutes)
    let seconds = getStringFrom(seconds: seconds)

    print("\(hours):\(minutes):\(seconds)")                
}

打印:

00:01:40

将数字转换为字符串形式的时间

func convertToHMS(number: Int) -> String {
  let hour    = number / 3600;
  let minute  = (number % 3600) / 60;
  let second = (number % 3600) % 60 ;
  
  var h = String(hour);
  var m = String(minute);
  var s = String(second);
  
  if h.count == 1{
      h = "0\(hour)";
  }
  if m.count == 1{
      m = "0\(minute)";
  }
  if s.count == 1{
      s = "0\(second)";
  }
  
  return "\(h):\(m):\(s)"
}
print(convertToHMS(number:3900))

我已经回答了类似的问题，但是你不需要在结果中显示毫秒。因此，我的解决方案需要iOS 10.0, tvOS 10.0, watchOS 3.0或macOS 10.12。

你应该调用func convertDurationUnitValueToOtherUnits(durationValue:durationUnit: smallstunitduration:)从我已经在这里提到的答案:

let secondsToConvert = 27005
let result: [Int] = convertDurationUnitValueToOtherUnits(
    durationValue: Double(secondsToConvert),
    durationUnit: .seconds,
    smallestUnitDuration: .seconds
)
print("\(result[0]) hours, \(result[1]) minutes, \(result[2]) seconds") // 7 hours, 30 minutes, 5 seconds