在警报控制器标题文本上设置倒数计时器

Question

我有一个警报控制器，它需要几分钟的输入并显示控制器标题的倒计时，还会突出显示所选的操作。

如何更新标题上的计时器，并使选定的操作加粗。我的警报控制器代码是：-

 let actionSheet = UIAlertController(title: "Set Timer", message: "--:--", preferredStyle: .actionSheet)
    let cancel = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)
    
    let time10 = UIAlertAction(title: "10 Minutes", style: .default) {
        
        action in
        self.totalTime = 600
        self.startTimer()
        
    }
    
    let time20 = UIAlertAction(title: "20 Minutes", style: .default) {
        
        action in
        self.totalTime = 1200
        self.startTimer()
    }
    
    let timeCustom = UIAlertAction(title: "Custom", style: .default) {
        
        action in
        self.performSegue(withIdentifier: "customTimer", sender: nil)
        
    }
    
    
    actionSheet.addAction(time10)
    actionSheet.addAction(time20)
    actionSheet.addAction(timeCustom)
    actionSheet.addAction(cancel)
    
    present(actionSheet, animated: true, completion: nil)
    
}

// startTimer()

func startTimer() {
        
        countdownTimer?.invalidate()

            countdownTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(updateTime), userInfo: nil, repeats: true)

    }
    @objc func updateTime() {
        
        print("update:- \(totalTime)")
        
        if totalTime != 0 {
            totalTime -= 1
        } else {
            
            endTimer()
        }
    }
    
    func endTimer() {
        print("end:- \(totalTime)")
    
        countdownTimer?.invalidate()
        
        print("timer end")
    }

Answer 1

将动作声明为实例属性并作为警报，用剩余时间更新消息，并在动作中定义首选动作：

    let actionSheet = UIAlertController?
    var totalTime = 600
    var time10 : UIAlertAction?
    var time20 : UIAlertAction?
    var timeCustom : UIAlertAction?

并且在动作初始化期间：

    actionSheet = UIAlertController(title: "Set Timer", message: "--:--", preferredStyle: .alert)
    time10 = UIAlertAction(title: "10 Minutes", style: .default) {
        action in
        self.totalTime = 600
        self.startTimer()
        self.actionSheet?.preferredAction = self.time10
    }

    time20 = UIAlertAction(title: "20 Minutes", style: .default) {

        action in
        self.totalTime = 1200
        self.startTimer()
        self.actionSheet?.preferredAction = self.time20
    }

    let timeCustom = UIAlertAction(title: "Custom", style: .default) {
        action in
        self.performSegue(withIdentifier: "customTimer", sender: nil)
        self.actionSheet?.preferredAction = self. and timertimeCustom
    }



@objc func updateTime() {
    
    print("update:- \(totalTime)")
    
    if totalTime != 0 {
        totalTime -= 1
    } else {        
        endTimer()
    }
    let hour = totalTime / 3600
    let minute = (totalTime - hour) / 60
    let seconds = (totalTime - hour) % 60
    actionSheet?.message = "\(hour):\(minute):\(seconds)"
}

第一次通话：

第二次通话：

Answer 2

Ptit Xav 的回答很好，但是有问题。当我第二次打开警报时应用程序崩溃。

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UIAlertController can only have one action with a style of UIAlertActionStyleCancel' terminating with uncaught exception of type NSException

我以某种方式解决了这个问题，这是一个小问题。

定义属性：-

let actionSheet : UIAlertController?
var totalTime = 600

var time10 : UIAlertAction?
var time20 : UIAlertAction?
var timeCustom : UIAlertAction?

然后在动作函数里面：-

func showActionSheetForSelectTimer() {
actionSheet = UIAlertController(title: "Set Timer", message: "--:--", preferredStyle: .actionSheet)
let cancel = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)
 time10 = UIAlertAction(title: "10 Minutes", style: .default) {
        action in
        self.totalTime = 600
        self.startTimer()
        self.actionSheet?.preferredAction = self.time10
    }

    time20 = UIAlertAction(title: "20 Minutes", style: .default) {

        action in
        self.totalTime = 1200
        self.startTimer()
        self.actionSheet?.preferredAction = self.time20
    }

    let timeCustom = UIAlertAction(title: "Custom", style: .default) {
        action in
        self.performSegue(withIdentifier: "customTimer", sender: nil)
        self.actionSheet?.preferredAction = self. and timertimeCustom
    }
        actionSheet?.addAction(cancel)
        actionSheet?.addAction(time10!)
        actionSheet?.addAction(time20!)
        actionSheet?.addAction(time30!)
        actionSheet?.addAction(time1!)
        actionSheet?.addAction(timeNever!)
        actionSheet?.addAction(timeCustom!)
        
        present(actionSheet!, animated: true, completion: nil)
        
    }
@objc func updateTime() {
    
    print("update:- \(totalTime)")
    
    if totalTime != 0 {
        totalTime -= 1
    } else {        
        endTimer()
    }
    let hour = totalTime / 3600
    let minute = (totalTime - hour) / 60
    let seconds = (totalTime - hour) % 60
    actionSheet.message = "\(hour):\(minute):\(seconds)"
}

在警报控制器标题文本上设置倒数计时器

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