Swift - Animate Image sequence - swift

Question

I have a list of images that I want to animate in Swift. I have tried to find the best possible way to do that - but I still have some problems.
The way I animate my image-list right now is by:
var animatedImage = UIImageView()
var velkomstImgList = [UIImage]()
override func viewDidAppear(_ animated: Bool) {
animatedImage.frame = CGRect(x: 0, y: 0, width: self.scrollView.frame.width, height: 200)
animatedImage.contentMode = .scaleAspectFit
scrollView.addSubview(animatedImage)
animateVelkomst()
}
func animateVelkomst() {
for i in 0...150 {
velkomstImgList.append(UIImage(named:"Velkomst_\(i).png")!)
if i == 150 {
self.animatedImage.animationImages = self.velkomstImgList
self.animatedImage.animationDuration = 5.0
self.animatedImage.startAnimating()
}
}
}
It works and the animation appears as expected. But the for loop in the beginning takes pretty long time and I dont think this is the right way to show the animation. Any suggestions on how I should animate the image sequence?

Answer 1

loading is slow because you are attempt to load 150 images same time. you can use timer and load image when you need it.
let imageCount = 150
var frameIndex = 0
var timer: Timer?
func startAnimation() {
frameIndex = 0
let deltaTime = 5.0 / Double(imageCount)
timer = Timer(timeInterval: deltaTime, target: self, selector: #selector(updateFrame), userInfo: nil, repeats: true)
}
func stopAnimation() {
timer?.invalidate()
timer = nil
}
#objc func updateFrame(_ timer: Timer) {
self.animatedImage.image = UIImage(named:"Velkomst_\(frameIndex).png")
frameIndex += 1
if frameIndex > imageCount {
frameIndex = 0
}
}