3秒钟不触摸时淡出按钮，用户触摸屏幕时淡入按钮

Question

Problem:

I have a UIButton that I'd like to fade out for a few seconds when the user doesn't touch the screen and fade them in when the user touches the screen. I think I might need to use a timer and some animation in the viewdidload part

@IBOutlet var startStopButton:  UIButton!

@IBAction func startStopButtonTapped(_ sender: UIButton) {

}


override func viewDidLoad() {
    super.viewDidLoad() }

Answer 1

I can help you here. Let me preface this answer with a usability concern. I'm not sure it makes sense to tap anywhere on the screen to reset (fade in) the button after X seconds (will the user know to do that?). You might want to add a button or some kind of text indicator to "tap here to reset the button(s)". This all ultimately depends on your application, but just throwing that out there :)

On with the answer!

The general idea here is you want to have a timer that runs a method every 1 second. If the timer hits zero, then you fade out and disable the startStop button. If the user taps anywhere on the screen (via gesture recognizer on the whole view), then fade the button in and enable it.

Now for the code part!

class ViewController: UIViewController {
// Create these 3 properties in the top of your class
var secondToFadeOut = 5 // How many second do you want the view to idle before the button fades. You can change this to whatever you'd like.
var timer = Timer() // Create the timer!
var isTimerRunning: Bool = false // Need this to prevent multiple timers from running at the same time.


@IBOutlet weak var startStopButton: UIButton! // The outlet for your button. This is used to fade it in and out, and enable / disable it.

override func viewDidLoad() {
    super.viewDidLoad()
    startStopButton.isEnabled = true
    runTimer()

    // Add a tap gesture recognizer to the main view to determine when the screen was tapped (for the purpose of resetting the timer).
    let tapRecognizer = UITapGestureRecognizer(target: self, action: #selector(self.tap(_:)))
    self.view.addGestureRecognizer(tapRecognizer)

}

func runTimer() {
    // Create the timer to run a method (in this case... updateTimer) every 1 second.
    timer = Timer.scheduledTimer(timeInterval: 1, target: self,   selector: (#selector(ViewController.updateTimer)), userInfo: nil, repeats: true)
    // Set the isTimerRunning bool to true
    isTimerRunning = true
}

@objc func updateTimer() {
    // Every 1 second that this method runs, 1 second will be chopped off the secondToFadeOut property. If that hits 0 (< 1), then run the fadeOutButton and invalidate the timer so it stops running.
    secondToFadeOut -= 1
    print(secondToFadeOut)
    if secondToFadeOut < 1 {
        fadeOutButton()
        timer.invalidate()
        isTimerRunning = false
    }
}

@objc func tap(_ gestureRecognizer: UITapGestureRecognizer) {
    // When the view is tapped (based on the gesture recognizer), reset the secondToFadeOut property, fade in (and enable) the button.
    //secondToFadeOut = 5
    fadeInButton()
    timer.invalidate()
    //if isTimerRunning == false {
    //    runTimer()
    //}
}

func fadeOutButton() {
    // Fade out your button! I also disabled it here. But you can do whatever your little heart desires.
    UIView.animate(withDuration: 0.5) {
        self.startStopButton.alpha = 0.25
    }
    self.startStopButton.isEnabled = false
}
func fadeInButton() {
    // Fade the button back in, and set it back to active (so it's tappable)
    UIView.animate(withDuration: 0.5) {
        self.startStopButton.alpha = 1
    }
    self.startStopButton.isEnabled = true
}


@IBAction func startStopButtonPressed(_ sender: UIButton) {
    print("Start Stop Button Pressed")
}
}

Hope that makes sense, but do let me know if you have any more questions!