如何使重启按钮出现时，计时器结束在Swift?

Question

我正在尝试在Swift中制作一个倒计时计时器。当计时器完成后，出现一个重启按钮，我想让计时器重新启动。

这是目前为止我的代码。

class TimerViewController: UIViewController {
let duration: Double = 5 // duration in seconds
var timer: Timer?
var progressView: UIProgressView!
var timeElapsed: Double = 0
override func viewDidLoad() {
super.viewDidLoad()
// Create the progress view
progressView = UIProgressView(progressViewStyle: .default)
progressView.frame = CGRect(x: 20, y: 100, width: view.frame.width - 40, height: 10)
progressView.progress = 0
view.addSubview(progressView)
// Create the timer
timer = Timer.scheduledTimer(timeInterval: 0.01, target: self, selector: #selector(timerFired), userInfo: nil, repeats: true)
}
@objc func timerFired() {
timeElapsed += 0.01
let progress = Float(timeElapsed / duration)
progressView.progress = progress

if timeElapsed >= duration {
timer?.invalidate()
timerEnded()
}
}
func timerEnded() {
// Timer has ended, do something here
// Show the restart button
print("Ended")
let restartButton = UIButton(frame: CGRect(x: 100, y: 100, width: 100, height: 50))
restartButton.setTitle("Restart", for: .normal)
restartButton.addTarget(self, action: #selector(restartTimer), for: .touchUpInside)
view.addSubview(restartButton)
}
@objc func restartTimer() {
// Restart the timer
timeElapsed = 0
progressView.progress = 0
timer?.invalidate()
timer = Timer.scheduledTimer(timeInterval: 0.01, target: self, selector: #selector(timerFired), userInfo: nil, repeats: true)
}
}

问题是计时器进度条显示得很好，但是重启按钮没有出现

Answer 1

你可能已经知道了，但如果你没有，我相信按钮是在那里，只是你看不见它。设置一个背景色，你应该能够看到按钮

在timerEnded按钮中设置按钮标题后添加以下语句

restartButton.backgroundColor = .gray

看看是否有帮助。