Swift : 暂停和恢复 NSTimer

Question

我知道之前已经发布过，但我是 swift 的新手，我想根据我的情况寻求帮助。所以我需要运行一个计时器，当调用 stopMusic() 时（在我的应用程序中的某个地方），我需要暂停计时器，然后当调用 playMusic() 时，我需要恢复计时器。

这是我所拥有的：

override func viewDidLoad() {

runFirstDropTimer = NSTimer.scheduledTimerWithTimeInterval(38.2, target: self, selector: "runAnimation", userInfo: nil, repeats: false)

}

func stopMusic() {
//Pause Timer
}

func playMusic() {
//Resume Timer
}

感谢您提供的任何帮助！！！

Answer 1

简答：你不能。计时器无法暂停。

相反，您需要在启动计时器时记录当前时间：

let startTime = NSDate.timeIntervalSinceReferenceDate()
let interval = 38.2
//Start your timer 
runFirstDropTimer = NSTimer.scheduledTimerWithTimeInterval(interval, 
  target: self, 
  selector: "runAnimation", 
  userInfo: nil, 
  repeats: false)

然后，当你想暂停你的计时器时，使它无效并计算还剩多少时间：

runFirstDropTimer.invalidate()
let elapsed = NSDate.timeIntervalSinceReferenceDate() - startTime
let remaining = interval - elapsed

最后，当您想恢复计时器时，创建一个具有 remaining 值的新计时器。

Answer 2

Swift 5.

可恢复计时器：

class ResumableTimer: NSObject {

    private var timer: Timer? = Timer()
    private var callback: () -> Void

    private var startTime: TimeInterval?
    private var elapsedTime: TimeInterval?

    // MARK: Init

    init(interval: Double, callback: @escaping () -> Void) {
        self.callback = callback
        self.interval = interval
    }

    // MARK: API

    var isRepeatable: Bool = false
    var interval: Double = 0.0

    func isPaused() -> Bool {
        guard let timer = timer else { return false }
        return !timer.isValid
    }

    func start() {
        runTimer(interval: interval)
    }

    func pause() {
        elapsedTime = Date.timeIntervalSinceReferenceDate - (startTime ?? 0.0)
        timer?.invalidate()
    }

    func resume() {
        interval -= elapsedTime ?? 0.0
        runTimer(interval: interval)
    }

    func invalidate() {
        timer?.invalidate()
    }

    func reset() {
        startTime = Date.timeIntervalSinceReferenceDate
        runTimer(interval: interval)
    }

    // MARK: Private

    private func runTimer(interval: Double) {
        startTime = Date.timeIntervalSinceReferenceDate

        timer = Timer.scheduledTimer(withTimeInterval: interval, repeats: isRepeatable) { [weak self] _ in
            self?.callback()
        }
    }
}

用法:

private var playTimer: ResumableTimer?

playTimer = ResumableTimer(interval: 5.0) { [weak self] in
   self?.doSomethingOnTimerFire()
}
playTimer?.start()

Swift : 暂停和恢复 NSTimer

Swift : Pause and Resume NSTimer

nstimer

swift