无法通过在 Swift 中将布尔值更改为 false 来停止计时器

Question

我尝试了运行下面的代码，但是计时器在计数到“0”秒后不会停止。

Desired OutPut : 5 seconds. 4 seconds. 3 seconds. 2 seconds. 1 seconds. 0 seconds.

class ViewController: UIViewController {
    var seconds = 5
    var value = true
    
    @IBAction
    func buttonPressed(_ sender: UIButton) {
        Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(secondsRemaining), userInfo: nil, repeats: value)
    }
            
    @objc
    func secondsRemaining() {
        print("\(seconds) seconds.")
        
        if seconds > 0{
            seconds -= 1
        }else{
            value = false
        }
    }
}

Answer 1

当您安排一个计时器将 true 作为 repeats 传递时，这意味着该计时器将继续发生，除非您在返回实例上显式调用 invalidate() 函数并将其设置为nil.

所以，您的代码应该是这样的：

class ViewController: UIViewController {
    var seconds = 5
    var timer: Timer?
    
    @IBAction func buttonPressed(_ sender: UIButton) {
        timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(secondsRemaining), userInfo: nil, repeats: true)
    }
    
   @objc func secondsRemaining() {
        print("\(seconds) seconds.")
        if seconds > 0 {
            seconds -= 1
        } else {
            timer?.invalidate()
            timer = nil
        }
    }
}

无法通过在 Swift 中将布尔值更改为 false 来停止计时器

Unable to stop the Timer by changing the Boolean value to false in Swift

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