ios - NSTimer 不工作 swift

Question

我以前见过几次，但我从来没有想过会出什么问题。

首先，我想创造出像电影中那些黑客场景中那样的数字加扰效果。因此，我制作了一个 NSTimer 来进行延迟，这样数字每 0.2 秒就会发生变化。然后，我制作了另一个计时器来告诉我的第一个计时器

invalidate() 

两秒后。我的代码如下:

import UIKit

class MainPage: UIViewController {

@IBOutlet var genericDeviceName: UITextField!
@IBOutlet var hackButton: UIButton!
@IBOutlet var rightNumber: UILabel!
@IBOutlet var leftNumber: UILabel!
@IBOutlet var detectionText: UILabel!

@IBAction func deviceNameEnter(sender: AnyObject) {
    detectionText.text = "Device detected: " + genericDeviceName.text!
    if genericDeviceName.text == "" {
        detectionText.text = "Error"
    }
    hackButton.alpha = 1
}


@IBAction func hackDevice(sender: AnyObject) {
    var tries = 0
    var timer = NSTimer()
    var timerStop = NSTimer()
    timer = NSTimer (timeInterval: 0.2, target: self, selector: "update", userInfo: nil, repeats: true)
    timerStop = NSTimer (timeInterval: 2, target: self, selector: "endTimer", userInfo: nil, repeats: true)

    let diceRoll = Int(arc4random_uniform(9) + 1)
    let diceRollSecond = Int(arc4random_uniform(9) + 1)

    UIView.animateWithDuration(0.25, animations:{
        self.hackButton.transform = CGAffineTransformMakeRotation(CGFloat(M_PI))})

        func update() {leftNumber.text = String(diceRoll)
        rightNumber.text = String(diceRoll)
    print("it worked!")}

    func endTimer() {

    timer.invalidate()
        detectionText.text = "Access Granted!"
        timerStop.invalidate()
    }
}

override func viewDidLoad() {
    super.viewDidLoad()
    self.view.backgroundColor = UIColor.blackColor()
}

那么...出了什么问题？最近几次我尝试使用 NSTimers，它们也没有用。我对 NSTimer 的概念有误吗？还是我的代码有错误？没有触发错误消息，只是计时器没有触发，数字也没有改变。甚至没有“它起作用了!”被打印到日志中。请通过建议一些代码来帮助。提前致谢!

更新

我已经更新了我的代码。在这里:

 import UIKit


 class MainPage: UIViewController {



@IBOutlet var genericDeviceName: UITextField!

@IBOutlet var hackButton: UIButton!
@IBOutlet var rightNumber: UILabel!
@IBOutlet var leftNumber: UILabel!
@IBOutlet var detectionText: UILabel!
@IBAction func deviceNameEnter(sender: AnyObject) {



    detectionText.text = "Device detected: " + genericDeviceName.text!

    if genericDeviceName.text == "" {detectionText.text = "Error"}



    hackButton.alpha = 1

}
let diceRoll = Int(arc4random_uniform(9) + 1)
    let diceRollSecond = Int(arc4random_uniform(9) + 1)

func update(timer: NSTimer) {leftNumber.text = String(diceRoll)
    rightNumber.text = String(diceRoll)
    print("it worked!")}

func endTimer(timerStop: NSTimer) {

    timer.invalidate()
    detectionText.text = "Access Granted!"
    timerStop.invalidate()}

@IBAction func hackDevice(sender: AnyObject) {




    var timer = NSTimer.scheduledTimerWithTimeInterval(0.2, target: self, selector: "update:", userInfo: nil, repeats: true)
    NSRunLoop.currentRunLoop().addTimer(timer, forMode: NSRunLoopCommonModes)
    var timerStop = NSTimer.scheduledTimerWithTimeInterval(2, target: self, selector: "endTimer:", userInfo: nil, repeats: true)
    NSRunLoop.currentRunLoop().addTimer(timerStop, forMode: NSRunLoopCommonModes)


    UIView.animateWithDuration(0.25, animations:{
        self.hackButton.transform = CGAffineTransformMakeRotation(CGFloat(M_PI))})



    }










override func viewDidLoad() {
    super.viewDidLoad()

    self.view.backgroundColor = UIColor.blackColor()


}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


/*
// MARK: - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    // Get the new view controller using segue.destinationViewController.
    // Pass the selected object to the new view controller.
}
*/

 }

目前，似乎函数“endTimer”不起作用，因为变量“timer”未被识别。请帮忙。非常感谢大家的宝贵时间!

Answer 1

一些事情:NSTimer 的选择器应该以冒号结尾(例如“更新:”或“endTimer:”并且该函数应该采用单个参数:NSTimer。

其次，定时器调用的函数必须是目标的顶层函数。您的更新方法是您的 hackDevice 函数的本地函数，该函数不起作用。

第三，您需要使用 scheduledTimerWithTimeInterval，如 ShahiM 的回答:

var timer = NSTimer.scheduledTimerWithTimeInterval(
  0.4, 
  target: self, 
  selector: "update:", 
  userInfo: nil, 
  repeats: true)

如果您的选择器中的函数是嵌套函数，则该代码会崩溃，因为它对计时器不可见。

最后，看起来您需要将变量 diceRoll 和 diceRollSecond 移出您的 hackDevice 函数，并使它们成为您的实例变量类。