Set a Countdown timer on Alert Controller Title text

Question

I have an Alert controller which will takes minute input and show the countdown to the title of the controller and also highlighted the selected action.

How can I update the timer on the title, and make bold the selected Action. My Alert controller code is:-

 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

Declare the action as instance property and as an alert ,update the message with the remaining time and also define the preferred action in the action in the action'action:

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

And during action initialisation :

    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)"
}

First call :

Second call :

Answer 2

Ptit Xav's answer is good, but it has a problem. When I open the alert for the second time app crashing.

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

Somehow I fix the problem, it is a minor fixing.

Define properties:-

let actionSheet : UIAlertController?
var totalTime = 600

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

Then inside the Action Function:-

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)"
}