How to show a message on screen for a few seconds?

Question

I want to display a message on screen after the user presses a button. I then want the message to disappear after about a second. Preferably it would fade away instead of a hard disappear.

I would rather not lock up the UI during the display of the message. In fact, I would like the timer to restart for the message if the button is pressed again. I'm unsure of whether to use NSTimer, dispatch_after, or if there are other options.

I currently plan to use an NSTimer and a UI label to achieve this, and I will just live with a hard disappear. Is that the best way to do it?

EDIT: To clarify, the message will not necessarily be the same every single time that the button is pushed. I'm not entirely sure if this is relevant though.

Answer 1

This shows an Alert View on screen and auto closes after 1 second. You can set the time.

 var alert:UIAlertController!
    func showAlert() {
        self.alert = UIAlertController(title: "Alert", message: "Wait Please!", preferredStyle: UIAlertControllerStyle.Alert)
        self.presentViewController(self.alert, animated: true, completion: nil)
        NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("dismissAlert"), userInfo: nil, repeats: false)
    }

    func dismissAlert(){
        // Dismiss the alert from here
        self.alert.dismissViewControllerAnimated(true, completion: nil)
    }

Answer 2

This code became shorter with iOS 10. Thanks to @fatihyildizhan

func showAlert() {
    let alert = UIAlertController(title: "Alert", message: "Wait Please!", preferredStyle: .alert)
    self.present(alert, animated: true, completion: nil)
    Timer.scheduledTimer(withTimeInterval: 3.0, repeats: false, block: { _ in alert.dismiss(animated: true, completion: nil)} )
}

Answer 3

I was able to accomplish what I wanted after researching what was suggested in the comment by @mn1. I used animateWithDuration to fade the label away. Here is some example code:

myLabel.hidden = false
UIView.animateWithDuration(0.5, animations: { () -> Void in
    self.myLabel.alpha = 0
})

Answer 4

the following solution

myLabel.hidden = false
UIView.animateWithDuration(0.5, animations: { () -> Void in
    self.myLabel.alpha = 0
})

got renamed to

UIView.animate(withDuration: 5.0, animations: { () -> Void in
        self.myLabel.alpha = 0
    })   

and don't forget to set your table in viewDidLoad to

mylabel.isHidden = true

Answer 5

For swift 5, taking from the excellent ideas above, the following creates a fading message using a simple function.

First create variable to call later.

    var fadingLabel: UILabel!

Create an initially hidden label in viewDidLoad() as follows (adjust the constraints as needed)

    // Fading Label
    fadingLabel = UILabel()
    fadingLabel.text = "Text"
    view.addSubview(fadingLabel)
    fadingLabel.isHidden = true

    fadingLabel.translatesAutoresizingMaskIntoConstraints = false
    fadingLabel.topAnchor.constraint    (equalTo: mapView.topAnchor,   constant:     60).isActive = true
    fadingLabel.leftAnchor.constraint   (equalTo: mapView.leftAnchor,  constant:     20).isActive = true
    fadingLabel.widthAnchor.constraint  (equalTo: mapView.widthAnchor, multiplier:  0.2).isActive = true
    fadingLabel.heightAnchor.constraint (equalToConstant: 20                           ).isActive = true

The following function will show a label and then fade it slowly away over three seconds.

func fadeMessage(message: String, color: UIColor, finalAlpha: CGFloat) {
    fadingLabel.text          = message
    fadingLabel.alpha         = 1.0
    fadingLabel.isHidden      = false
    fadingLabel.textAlignment = .center
    fadingLabel.backgroundColor     = color
    fadingLabel.layer.cornerRadius  = 5
    fadingLabel.layer.masksToBounds = true
    fadingLabel.font = appBoldFont(size: 14.0)
    UIView.animate(withDuration: 3.0, animations: { () -> Void in
        self.fadingLabel.alpha = finalAlpha
    })
}

As an example, call the function using,

fadeMessage(message: "Saved", color: .blue, finalAlpha: 0.0)

Set the final alpha to about 0.4 if you want the message to remain discreetly, or to zero if you want it to disappear.