如何动画SwiftUI中的图片，播放一帧animation

Question

I want to animate images in SwiftUI's Image view

First, I tried creating some variables and a function to toggle the Image("imageVariable"). It changes but there is no animation even tried the withAnimation { } method

Secondly, I tried to use a UIKit view. Here, the animation works but I can't apply the resizable() modifier or a set a fixed frame

var images: [UIImage]! = [UIImage(named: "pushup001")!, UIImage(named: "pushup002")!]

let animatedImage = UIImage.animatedImage(with: images, duration: 0.5)

struct workoutAnimation: UIViewRepresentable {

    func makeUIView(context: Self.Context) -> UIImageView {
        return UIImageView(image: animatedImage)
    }

    func updateUIView(_ uiView: UIImageView, context: UIViewRepresentableContext<workoutAnimation>) {

    }
}


struct WorkoutView: View {
    var body: some View {
        VStack {
            workoutAnimation().aspectRatio(contentMode: .fit)
        }
    }
}

In method 1 I can change the image but not animate, while, in method 2 I can animate but not control it's size

Answer 1

If you want a robust and cross-platform SwiftUI implementation for animated images, like GIF/APNG/WebP, I recommend using SDWebImageSwiftUI . This framework is based on exist success image loading framework SDWebImage and provides a SwiftUI binding.

To play the animation, use AnimatedImage view.

var body: some View {
    Group {
        // Network
        AnimatedImage(url: URL(string: "https://raw.githubusercontent.com/liyong03/YLGIFImage/master/YLGIFImageDemo/YLGIFImageDemo/joy.gif"))
        .onFailure(perform: { (error) in
            // Error
        })
    }
}

Answer 2

I solved this using UIViewRepresentable protocol. Here I returned a UIView with the ImageView as it's subview. This gave me more control over the child's size, etc.

import SwiftUI


var images : [UIImage]! = [UIImage(named: "pushup001")!, UIImage(named: "pushup002")!]

let animatedImage = UIImage.animatedImage(with: images, duration: 0.5)

struct workoutAnimation: UIViewRepresentable {

    func makeUIView(context: Self.Context) -> UIView {
        let someView = UIView(frame: CGRect(x: 0, y: 0, width: 400, height: 400))
        let someImage = UIImageView(frame: CGRect(x: 20, y: 100, width: 360, height: 180))
        someImage.clipsToBounds = true
        someImage.layer.cornerRadius = 20
        someImage.autoresizesSubviews = true
        someImage.contentMode = UIView.ContentMode.scaleAspectFill
        someImage.image = animatedImage
        someView.addSubview(someImage)
        return someView
    }

    func updateUIView(_ uiView: UIView, context: UIViewRepresentableContext<workoutAnimation>) {

    }
}


struct WorkoutView: View {
    var body: some View {
        VStack (alignment: HorizontalAlignment.center, spacing: 10) {
            workoutAnimation()
            Text("zzzz")
        }
    }
}

Answer 3

thanks for the ImageAnimated class! it comes in handy! one thing, the duration should be a var instead of a constant if you intend to pass the value in. otherwise you have to leave duration out of the ImageAnimated(imageSize:imageNames:) call. :)

var duration: Double = 0.5

Answer 4

I have created an image animation class that can be easily reused

import SwiftUI

struct ImageAnimated: UIViewRepresentable {
    let imageSize: CGSize
    let imageNames: [String]
    let duration: Double = 0.5

    func makeUIView(context: Self.Context) -> UIView {
        let containerView = UIView(frame: CGRect(x: 0, y: 0
            , width: imageSize.width, height: imageSize.height))

        let animationImageView = UIImageView(frame: CGRect(x: 0, y: 0, width: imageSize.width, height: imageSize.height))

        animationImageView.clipsToBounds = true
        animationImageView.layer.cornerRadius = 5
        animationImageView.autoresizesSubviews = true
        animationImageView.contentMode = UIView.ContentMode.scaleAspectFill

        var images = [UIImage]()
        imageNames.forEach { imageName in
            if let img = UIImage(named: imageName) {
                images.append(img)
            }
        }

        animationImageView.image = UIImage.animatedImage(with: images, duration: duration)

        containerView.addSubview(animationImageView)

        return containerView
    }

    func updateUIView(_ uiView: UIView, context: UIViewRepresentableContext<ImageAnimated>) {

    }
}

The way to use it:

ImageAnimated(imageSize: CGSize(width: size, height: size), imageNames: ["loading1","loading2","loading3","loading4"], duration: 0.3)
                        .frame(width: size, height: size, alignment: .center)

Answer 5

in model :

var publisher : Timer?

@Published var index = 0

func startTimer() {
        index = 0
        publisher = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true, block: {_ in
            if self.index < count/*count of frames*/{
                self.index += 1
            }
            else if let timer = self.publisher {
                timer.invalidate()
                self.publisher = nil
            }
        })
  }
}

in view :

struct MyAnimationView : View {


let width : CGFloat
let images = (0...60).map { UIImage(named: "tile\($0)")! }
@StateObject var viewmodel : MyViewModel

var body: some View {
    Image(uiImage: images[viewmodel.index])
        .resizable()
        .frame(width: width, height: width, alignment: .center)
         
}
}