Swift Timer无法在旧版iPhone上正常运行

由九尾狐发布于 2020-04-09 03:08:40

我遇到了Swift计时器问题。计时器在iPhone 6等旧版iPhone上无法正常使用。当我打印出时间时，计时器每2秒将1秒计数一次。但是，如果我将TimeInterval更改为0.05，则效果会更好一些。但是仍然不能像现实生活中那样工作。这是我的代码。谁能帮我？

weak var timer: Timer?
var startTime: Double = 0

 func configureTimer(totalSecond: Double) {

    self.startTime = 0
    self.invalidateTimer()

    DispatchQueue.main.async {
        self.timer = Timer.scheduledTimer(timeInterval: 0.01,target: self,selector: #selector(self.advanceTimer(timer:)),userInfo: nil,repeats: true)

    }

}

@objc func advanceTimer(timer: Timer) {

    time = Date().timeIntervalSinceReferenceDate - startTime

    startTime += 0.01

    print("Timer \(startTime)")

    self.questionView.configureProgressBar(totalTime: Double(self.totalSecond), elapsingTime: startTime)
    self.isTimeExpired = false

    if Int(startTime) == Int(totalSecond) {

        self.timer!.invalidate()
        self.isTimeExpired = true
        self.userAnswerIndex = -1
        self.sendAnswer(index: self.userAnswerIndex, isTimeExpired: self.isTimeExpired)
    }

}

浅唱夜旳美

2020-04-09 03:08:40

我会尝试像这样设置。

var myTimer = Timer()
var counter = 0.0

myTimer = Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(yourTargetFunctionHere), userInfo: nil, repeats: true)

@objc func yourTargetFunctionHere() { 
     //in here is where you do all your code work
     counter += 0.1
     if counter == yourElapsedTime {
         //when your target time is hit do something here
     }
     if counter == finishedTime {
       self.timer.invalidate()
       self.counter = 0
     }
}

eipsum

2020-04-09 03:08:40

计时器不是很精确。我认为精度约为0.05秒。而且，如果一个过程需要大量电能，那么您的计时器就会更加慢下来。解决方案可以是节省启动计时器的时间，并且每次启动计时器时，您都可以进行数学运算来知道经过了多少时间：

class YourClass {

var startTime : TimeInterval!

//...

func configureTimer() {
    startTime = Date().timeIntervalSinceReferenceDate //You add this line

    elapsingTime = 0.0
    timer?.invalidate()

    DispatchQueue.main.async {

        self.timer = Timer.scheduledTimer(withTimeInterval: 0.01, repeats: true, block: { [weak self] timer in

            guard let self = self else { return }

            self.elapsingTime = Date().timeIntervalSinceReferenceDate - self.startTime //You change this one
            self.questionView.configureProgressBar(totalTime: self.totalTime, elapsingTime: self.elapsingTime)
            self.questionView.videoQuestionPlayer.player?.play()
            if Int(self.elapsingTime) == Int(self.totalTime) {

                self.timer!.invalidate()
                self.isTimeExpired = true
                self.sendAnswer(index: -1)
            }
        })
    }
}

}

九尾狐

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