ios - Swift 中 for 循环中的计时器

Question

我只想在给定循环次数的循环内运行计时器。还有一个外环。

用户将输入他想要重复多少次，每次重复多少次计数，两次计数之间的时间间隔。

应用程序将显示每次重复的次数。完成所有重复后，应用程序将停止计时器。

但是我觉得很难。看起来 timer 忽略了 for 循环，它本身就是一个循环，当我们仅发出 timer.invalidate() 时停止。

有什么想法吗？

for x in 0...HowManyRepetitions {

                counter = 0
                CountLabel.text = "\(counter)"
                RepetitionLabel.text = "\(x) / \(HowManyRepetitions)"

                for y in 0...HowManyCounts {

                    timer = NSTimer.scheduledTimerWithTimeInterval(PeriodBetween, target: self, selector: updateCounter, userInfo: nil, repeats: true)

                }

            }

Answer 1

需要在计时器处理程序中管理重复计数。

您通常将计时器作为实例属性。 (您可能需要使计时器无效，例如，当 viewWillDisappear(_:) 时。)

所以，你可能需要在类里面写这样的东西:

var timer: NSTimer?
func startTimer(howManyCounts: Int, periodBetween: NSTimeInterval) {
    let userInfo: NSMutableDictionary = [
        "counter": 0,
        "howManyCounts": howManyCounts,
        "myName": "Timer"
    ]
    self.timer = NSTimer.scheduledTimerWithTimeInterval(periodBetween, target: self, selector: #selector(timerHandler), userInfo: userInfo, repeats: true)
}

@objc func timerHandler(timer: NSTimer) {
    guard let info = timer.userInfo as? NSMutableDictionary else {
        return
    }
    var counter = info["counter"] as? Int ?? 0
    let howManyCounts = info["howManyCounts"] as? Int ?? 0
    let myName = info["myName"] as? String ?? "Timer"
    counter += 1

    print("\(myName):\(counter)") //countLabel.text = "\(counter)"

    if counter >= howManyCounts {
        timer.invalidate()
    } else {
        info["counter"] = counter
    }
}

从与以下相同类的方法中的某处启动计时器:

    startTimer(10, periodBetween: 3.0)

---

我不明白为什么你需要外循环，但如果你想让多个定时器工作，你需要保留所有定时器。

var timers: [NSTimer] = []
func startTimers(howManyRepetitions: Int, howManyCounts: Int, periodBetween: NSTimeInterval) {
    timers = []
    for x in 1...howManyRepetitions {
        let userInfo: NSMutableDictionary = [
            "counter": 0,
            "howManyCounts": howManyCounts,
            "myName": "Timer-\(x)"
        ]
        timers.append(NSTimer.scheduledTimerWithTimeInterval(periodBetween, target: self, selector: #selector(timerHandler), userInfo: userInfo, repeats: true))
    }
}

启动计时器为:

    startTimers(3, howManyCounts: 4, periodBetween: 1.0)