Swift UIView appearing in different places - ios

Question

Im trying to make a small game. And there is some problem with the animation. Im new to Swift. So lets take a look. I create a UIImageView picture and want to do animation of this picture appear in a different places on a screen. I believe that the algorithm will look like this:
Infinite loop{
1-GetRandomPlace
2-change opacity from 0 to 1 and back(with smooth transition)
}
Looks simple, but I can't understand how to do it correctly in Xcode.
Here is my test code but it looks useless
Thank you for help and sorry if there was already this question, I can't find it.
class ViewController: UIViewController {
#IBOutlet weak var BackgroundMainMenu:UIImageView!
#IBOutlet weak var AnimationinMenu: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
// MoveBackgroundObject(AnimationinMenu)
// AnimationBackgroundDots(AnimationinMenu, delay: 0.0)
// self.AnimationinMenu.alpha = 0
//
// UIImageView.animateWithDuration(3.0,
// delay: 0.0,
// options: UIViewAnimationOptions([.Repeat, .CurveEaseInOut]),
// animations: {
// self.MoveBackgroundObject(self.AnimationinMenu)
// self.AnimationinMenu.alpha = 1
// self.AnimationinMenu.alpha = 0
// },
// completion: nil)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override func viewWillAppear(animated: Bool) {
AnimationBackgroundDots(AnimationinMenu, delay: 0.0)
}
func ChangeOpacityto1(element: UIImageView){
element.alpha = 0
UIView.animateWithDuration(3.0) {
element.alpha = 1
}
}
func ChangeOpacityto0(element: UIImageView){
element.alpha = 1
UIView.animateWithDuration(3.0){
element.alpha = 0
}
}
func AnimationBackgroundDots(element: UIImageView, delay: Double){
element.alpha = 0
var z = 0
while (z<4){
MoveBackgroundObject(AnimationinMenu)
UIImageView.animateWithDuration(3.0,
animations: {
element.alpha = 0
element.alpha = 1
element.alpha = 0
},
completion: nil)
z++
}
}
func MoveBackgroundObject(element: UIImageView) {
// Find the button's width and height
let elementWidth = element.frame.width
let elementHeight = element.frame.height
// Find the width and height of the enclosing view
let viewWidth = BackgroundMainMenu.superview!.bounds.width
let viewHeight = BackgroundMainMenu.superview!.bounds.height
// Compute width and height of the area to contain the button's center
let xwidth = viewWidth - elementWidth
let yheight = viewHeight - elementHeight
// Generate a random x and y offset
let xoffset = CGFloat(arc4random_uniform(UInt32(xwidth)))
let yoffset = CGFloat(arc4random_uniform(UInt32(yheight)))
// Offset the button's center by the random offsets.
element.center.x = xoffset + elementWidth / 2
element.center.y = yoffset + elementHeight / 2
}
}

Answer 1

The problem is in AnimationBackgroundDots.
You are immediately creating 4 animations on the same view but only one can run at a time. What you need to do is wait until one animation is finished (fade in or fade out) before starting a new one.
Also, the animations closure is for setting the state you want your view to animate to. It looks at how your view is at the start, runs animations, then looks at the view again and figures out how to animate between the two. In your case, the alpha of the UIImageView starts at 0, then when animations runs, the alpha ends up being 0 so nothing would animate. You can't create all the steps an animation should take that way.
Want you need to do it move your view and start the fade in animation. The completion closure of fading in should start the fade out animation. The completion closure of the fading out should then start the process all over again. It could look something like this.
func AnimationBackgroundDots(element: UIImageView, times: Int) {
guard times > 0 else {
return
}
MoveBackgroundObject(element)
element.alpha = 1
// Fade in
UIView.animateWithDuration(3.0, animations: {
element.alpha = 1
}, completion: { finished in
// Fade Out
UIView.animateWithDuration(3.0, animations: {
element.alpha = 0
}, completion: { finished in
// Start over again
self.AnimationBackgroundDots(element, times: times-1)
})
})
}
You called also look at using keyframe animations but this case is simple enough that theres no benefit using them.
Also as a side note. The function naming convention in swift is to start with a lowercase letter, so AnimationBackgroundDots should be animationBackgroundDots.