如何在 SwiftUI 中为图像设置动画，播放帧动画

Question

我想在 SwiftUI 的图像视图中为图像设置动画

首先，我尝试创建一些变量和一个函数来切换 Image("imageVariable")。它改变了但没有动画甚至尝试了withAnimation { }方法

其次，我尝试使用 UIKit 视图。在这里，动画有效，但我无法应用 resizable() 修饰符或设置固定帧

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)
        }
    }
}

在方法 1 中我可以更改图像但不能动画，而在方法 2 中我可以动画但不能控制它的大小

Answer 1

如果您想要为动画图像（如 GIF/APNG/WebP）提供强大且跨平台的 SwiftUI 实现，我建议使用 SDWebImageSwiftUI。该框架基于现有的成功图片加载框架SDWebImage，并提供SwiftUI绑定。

要播放动画，请使用AnimatedImage 视图。

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

我使用UIViewRepresentable 协议解决了这个问题。在这里，我返回了 UIView 和 ImageView 作为子视图。这让我可以更好地控制孩子的大小等。

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

在模型中：

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
            }
        })
  }
}

在视图中：

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)
         
}
}

Answer 4

我创建了一个可以轻松重用的图像动画类

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>) {

    }
}

使用方法：

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