How to apply an animation effect to UIImageView slideshow - ios

Question

On Swift 3.0 how can I apply some animation effect to this slideshow? Cannot find animation effects related to animationWithDuration method.
let image1 = UIImage(named: "image1")!
let image2 = UIImage(named: "image2")!
let image3 = UIImage(named: "image3")!
var imagesArray : [UIImage] = []
override func viewDidLoad() {
super.viewDidLoad()
imagesArray = [image1, image2, image3]
myView.clipsToBounds = true
myView.animationImages = imagesArray
myView.animationDuration = 10.0
myView.animationRepeatCount = 0
myView.startAnimating()
}

Answer 1

It looks like you are using the build in frame animation for UIImageView. This is designed to just cycle through the images, like an animated gif. It doesn't really have more sophisticated animation than that. What you can do if you want transition effects is alternate between two image views and use the UIView Animation methods to switch between them. This just does a crossfade by manipulating alpha:
var images = [UIImage]()
var currentImageindex = 0
func animateImageViews() {
swap(&firstImageView, &secondImageView)
secondImageView.image = images[currentImageindex]
currentImageindex = (currentImageindex + 1) % images.count
UIView.animate(withDuration: 1, animations: {
self.firstImageView.alpha = 0
self.secondImageView.alpha = 1
}, completion: { _ in
self.animateImageViews()
})
}
Here is playground that shows how it works. You need to drop 2 images into the resources folder named 1.png and 2.png for it to work. Note that setting the view frames like this is horrible programming practice i just did it here for brevity. use interface builder and autolayout in your actual code.
import PlaygroundSupport
import UIKit
class Demo: UIViewController {
let button = UIButton()
var firstImageView = UIImageView()
var secondImageView = UIImageView()
var images = [UIImage]()
var currentImageindex = 0
override func viewDidLoad() {
view.addSubview(firstImageView)
view.addSubview(secondImageView)
images.append(UIImage(named: "1.png")!)
images.append(UIImage(named: "2.png")!)
firstImageView.image = images[0]
secondImageView.image = images[1]
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
firstImageView.frame = view.frame
secondImageView.frame = view.frame
}
override func viewDidAppear(_ animated: Bool) {
animateImageViews()
}
func animateImageViews() {
swap(&firstImageView, &secondImageView)
secondImageView.image = images[currentImageindex]
currentImageindex = (currentImageindex + 1) % images.count
UIView.animate(withDuration: 1, animations: {
self.firstImageView.alpha = 0
self.secondImageView.alpha = 1
}, completion: { _ in
self.animateImageViews()
})
}
}
let viewcontroller = Demo()
viewcontroller.view.frame = CGRect(x: 0, y: 0, width: 100, height: 100)
PlaygroundPage.current.liveView = viewcontroller.view