如何在Swift 2的SOS中创建闪光灯LED?

问题描述

我尝试在iPhone中基于手电筒/闪光灯编写小型程序.现在我想添加SOS信号，但我不知道该怎么做.在此代码中，当我启动程序时，程序将每0.2秒打开和关闭我的LED一次.但我不知道如何在SOS信号中执行此操作.并且当用户单击SOS ON并单击SOS OFF时，led应立即关闭.我需要运行一些线程吗?还是在NSTimer上?

I tried write small program base on torch/flash in iPhones. Now i want add SOS signal but i have no idea how should do this. In this code when i start program will switch on and off my LED every 0.2 sec. But i don't know how to do this in SOS signal. And when user click SOS ON and click SOS OFF led should be off immediately. Do i need running some Thread ? or on NSTimer ?

class Sos {
    var timer1 = NSTimer()
    var timer2 = NSTimer()
    var volume: Float = 0.1
    let flashLight = FlashLight()

    func start() {

        self.timer1 = NSTimer.scheduledTimerWithTimeInterval(0.2,
            target: self,
            selector: Selector("switchON"),
            userInfo: nil,
            repeats: true)

        self.timer2 = NSTimer.scheduledTimerWithTimeInterval(0.4,
            target: self,
            selector: Selector("switchOFF"),
            userInfo: nil,
            repeats: true)
    }

    func stop() {
        timer1.invalidate()
        timer2.invalidate()
        flashLight.switchOFF()
    }


    @objc func switchON() {
        flashLight.switchON(self.volume)
    }

    @objc func switchOFF() {
        flashLight.switchOFF()
    }

    deinit {
        self.timer1.invalidate()
        self.timer2.invalidate()
    }

}

推荐答案

有很多方法可以实现它.创建时间间隔序列，例如在开/关之间切换.代码注释.

Many ways to achieve it. Create sequence of time intervals and alternate between on/off for example. Comments in code.

///
/// SOS sequence: ...---...
///
/// . short
/// - long
///
class SOS {
  /// Short signal duration (LED on)
  private static let shortInterval = 0.2
  /// Long signal duration (LED on)
  private static let longInterval = 0.4
  /// Pause between signals (LED off)
  private static let pauseInterval = 0.2
  /// Pause between the whole SOS sequences (LED off)
  private static let sequencePauseInterval = 2.0

  /**
    When the SOS sequence is started flashlight is on. Thus
    the first time interval is for the short signal. Then pause,
    then short, ...

    See `timerTick()`, it alternates flashlight status (on/off) based
    on the current index in this sequence.
  */
  private let sequenceIntervals = [
    shortInterval, pauseInterval, shortInterval, pauseInterval, shortInterval, pauseInterval,
    longInterval, pauseInterval, longInterval, pauseInterval, longInterval, pauseInterval,
    shortInterval, pauseInterval, shortInterval, pauseInterval, shortInterval, sequencePauseInterval
  ]

  /// Current index in the SOS `sequence`
  private var index: Int = 0

  /// Non repeatable timer, because time interval varies
  private weak var timer: NSTimer?

  /**
    Put your `Flashlight()` calls inside this function.

    - parameter on: pass `true` to turn it on or `false` to turn it off
  */
  private func turnFlashlight(on on: Bool) {
    // if on == true  -> turn it on
    // if on == false -> turn it off
    print(on ? "ON" : "OFF")
  }

  private func scheduleTimer() {
    timer = NSTimer.scheduledTimerWithTimeInterval(sequenceIntervals[index],
      target: self, selector: "timerTick",
      userInfo: nil, repeats: false)
  }

  @objc private func timerTick() {
    // Increase sequence index, at the end?
    if ++index == sequenceIntervals.count {
      // Start from the beginning
      index = 0
    }
    // Alternate flashlight status based on current index
    // index % 2 == 0 -> is index even number? 0, 2, 4, 6, ...
    turnFlashlight(on: index % 2 == 0)
    scheduleTimer()
  }

  func start() {
    index = 0
    turnFlashlight(on: true)
    scheduleTimer()
  }

  func stop() {
    timer?.invalidate()
    turnFlashlight(on: false)
  }

  deinit {
    timer?.invalidate()
  }
}

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