ios - swift |计时器不会在无效调用时停止，而是加速？

Question

我在此应用程序中使用计时器制作了一个秒表，并添加了开始停止按钮以暂停和播放相同的内容。当按下按钮时，它被发送到一个使计时器无效的函数，它应该停止。但奇怪的是，当按下停止按钮时，计时器并没有停止而是以某种方式加速除了一次声明之外，我没有更改时间间隔。

我曾尝试在按下开始按钮后将其禁用，甚至将其隐藏。还尝试更改时间间隔但没有任何效果。我越按开始停止按钮，它越加速，开始比提到的时间间隔快得多。

startButton.frame = CGRect(x: 0, y: UIScreen.main.bounds.height * 0.9 , width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height * 0.1)
    startButton.setTitle("Start Timer", for: .normal)
    self.view.addSubview(startButton)
    startButton.setTitleColor(.white , for: .normal)
    startButton.backgroundColor = .red
    startButton.addTarget(self, action: #selector(playButton(_:)), for: .allTouchEvents)

    stopButton.frame = CGRect(x: 0, y: UIScreen.main.bounds.height * 0.9 , width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height * 0.1)
    stopButton.setTitle("Stop Timer", for: .normal)
    stopButton.setTitleColor(.white , for: .normal)
    stopButton.backgroundColor = .red
    stopButton.addTarget(self, action: #selector(pauseButton(_:)), for: .allTouchEvents)
@objc func playButton(_ sender : Any)
{
    timer = Timer.scheduledTimer(timeInterval: 1, target: self , selector: #selector(updateTimer), userInfo: nil, repeats: true)
    startButton.isEnabled = false
    stopButton.isEnabled = true
    isRunning = true
    self.view.addSubview(stopButton)
    startButton.isHidden = true
    stopButton.isHidden = false



}

@objc func pauseButton(_ sender: Any) {
    self.view.addSubview(startButton)
    timer.invalidate()

    stopButton.isHidden = true
    startButton.isHidden = false

    startButton.isEnabled = true
    stopButton.isEnabled = false

    isRunning = false

}


@objc func updateTimer(_ sender : Any)
{
    counter += 0.1
    titleLabel.text = String(format: "%.1f", counter)
}

Answer 1

据我所知，你有 2 个错误。

另一个答案提到了第一个。这是一个真实的建议，你不应该总是添加一个新的 UIButton 并且应该只为每个按钮使用 hide/unhide 属性。

第二个错误在于添加目标的方式。您正在使用 .allTouchEvents，但是您可能打算使用 .touchUpInside 作为您的控制状态。

请参阅以下更正后的代码供您引用:

import UIKit

class ViewController: UIViewController {

@IBOutlet weak var titleLabel: UILabel!

var startButton: UIButton!
var stopButton: UIButton!
var timer: Timer!
var counter: Double = 0.0

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    startButton = UIButton(frame: CGRect(x: 0, y: UIScreen.main.bounds.height * 0.9 , width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height * 0.1))
    startButton.setTitle("Start Timer", for: .normal)
    startButton.setTitleColor(.white , for: .normal)
    startButton.backgroundColor = .red
    startButton.addTarget(self, action: #selector(playButton(_:)), for: .touchUpInside)
    self.view.addSubview(startButton)
    self.startButton.isHidden = false

    stopButton = UIButton(frame: CGRect(x: 0, y: UIScreen.main.bounds.height * 0.9 , width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height * 0.1))
    stopButton.setTitle("Stop Timer", for: .normal)
    stopButton.setTitleColor(.white , for: .normal)
    stopButton.backgroundColor = .red
    stopButton.addTarget(self, action: #selector(pauseButton(_:)), for: .touchUpInside)
    self.view.addSubview(stopButton)
    self.stopButton.isHidden = true
}

@objc func playButton(_ sender : Any) {
    timer = Timer.scheduledTimer(timeInterval: 1, target: self , selector: #selector(updateTimer), userInfo: nil, repeats: true)

    startButton.isEnabled = false
    stopButton.isEnabled = true
    startButton.isHidden = true
    stopButton.isHidden = false
}

@objc func pauseButton(_ sender: Any) {
    timer.invalidate()

    stopButton.isHidden = true
    startButton.isHidden = false
    startButton.isEnabled = true
    stopButton.isEnabled = false
}


@objc func updateTimer(_ sender : Any)
{
    counter += 0.1
    titleLabel.text = String(format: "%.1f", counter)
}
}