How to wait until an animation is finished in Swift?

Question

I try to let a button "shake" before the next question of my quiz is going to load.

The animation looks like

var timer = NSTimer()
    UIView.animateWithDuration(0.1, animations: {
        self.IMGVIEWcat.center = CGPointMake(self.IMGVIEWcat.center.x + 2, self.IMGVIEWcat.center.y)
    })
    UIView.animateWithDuration(0.2, animations: {
        self.IMGVIEWcat.center = CGPointMake(self.IMGVIEWcat.center.x - 4, self.IMGVIEWcat.center.y)
    })
    UIView.animateWithDuration(0.3, animations: {
            self.IMGVIEWcat.center = CGPointMake(self.IMGVIEWcat.center.x + 2, self.IMGVIEWcat.center.y)
    })

After this the following function is called

    func QueryInformations(){
        println("QueryInformationsStart")
        self.ActivityIndicator.hidden = false
        ObjectIDsArrayCount = ObjectIDsArray.count
        var RandomQuestion = Int(arc4random_uniform(ObjectIDsArray.count + 0))
        var QuestionID:String = ObjectIDsArray[RandomQuestion]
        var query : PFQuery = PFQuery(className: "AddonQuiz")
        query.getObjectInBackgroundWithId(QuestionID){
            (ObjectHolder : PFObject!, error : NSError!) -> Void in
...

Now the animation starts but instant the next question is loaded, is there some easy wait for a beginner to implement a "waiting" until the animation is done?

I tried to set

var complet == true 

In the animation

And in the query function

if complet = true {....

But this did not work for me, also I found some information about completion handler but didn't get it work in my code.

Solution 1

If you want to use the completion block at the end of the animation, you should use constructs with the delay and options arguments as well.

UIView.animateWithDuration(0.3, delay: 0.0, options: UIViewAnimationOptions.CurveLinear, animations: { 
// put here the code you would like to animate
    self.IMGVIEWcat.center = CGPointMake(self.IMGVIEWcat.center.x + 2, self.IMGVIEWcat.center.y)

}, completion: {(finished:Bool) in
// the code you put here will be compiled once the animation finishes
    QueryInformations() 
})

Solution 2

Use the completion block on that function you're calling:

UIView.animateWithDuration(0.3, animations: {
        self.IMGVIEWcat.center = CGPointMake(self.IMGVIEWcat.center.x + 2, self.IMGVIEWcat.center.y)
}, completion: {(finished:Bool) in
  QueryInformations()
})

Comments

[Fabian Boulegue]

This currently gives me a error, "missing argument for delay"

[Fabian Boulegue]

getting a error on "}, completion: {" 'Bool' is not a Subtype of '()'

[Cesare]

Glad you got it working! it's really important you understand the options: nil block. Instead of nil you could use UIViewAnimationOptions.CurveLinear or UIViewAnimationOptions.CurveEaseOut. These settings modify how the animation behaves. If you use the last one the animation will begin quickly and the it will slow down as the animation completes.

[Fabian Boulegue]

What you mean by UIViewAnimationOptions.CurveLinear or UIViewAnimationOptions.CurveEaseOut

[Fabian Boulegue]

Let us continue this discussion in chat.

[Ian MacDonald]

It shouldn't. Taken straight from developer.apple.com/library/ios/documentation/UIKit/Referenc‌​e/…: