SwiftUI，将可扩展的 UIImage 放入 ScrollView

Question

我有一个例程，允许用户从他们的照片库中选择图像。 然后我希望能够通过捏合手势缩放图像。我有那个工作：

struct ContentView: View {
    @State private var selected : PhotosPickerItem?
    @State private var picture : UIImage?
    @GestureState private var magnification : CGFloat = 1
    @State private var zoom : CGFloat = 1
    
    var body: some View {
        NavigationStack {
            ScrollView([.vertical, .horizontal]) {
                VStack {
                    Image(uiImage: picture ?? UIImage(named: "nopicture")!)
                        .resizable()
                        .scaledToFit()
                        .scaleEffect(getCurrentZoom(magnification: magnification))
                        .gesture(MagnificationGesture()
                            .updating($magnification) { value, state, transaction in
                                state = value
                            }
                            .onEnded { value in
                                zoom = getCurrentZoom(magnification: value)
                            })
                }
            }
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    PhotosPicker(selection: $selected, matching: .images, photoLibrary: .shared()) { Text("Select a Photo") }
                }
            }
            .onChange(of: selected) { item in
                Task(priority: .background) {
                    if let data = try? await item?.loadTransferable(type: Data.self) {
                        picture = UIImage(data: data)
                    }
                }
            }
        }
    }
    func getCurrentZoom(magnification : CGFloat) -> CGFloat {
        let minZoom : CGFloat = 1
        let maxZoom : CGFloat = 4
        var current = zoom * magnification
        current = max(min(current, maxZoom), minZoom)
        return current
    }
}

但是我现在正试图滚动放大的图像。 我试图将它放入 ScrollView 但是当图像被加载时它已经放大非常大并且我无法缩小它（尽管它仍然可以按比例放大。） 这是我正在尝试的代码，ScrollView 包含包含 UIImage 的 VStack：

struct ContentView: View {
    @State private var selected : PhotosPickerItem?
    @State private var picture : UIImage?
    @GestureState private var magnification : CGFloat = 1
    @State private var zoom : CGFloat = 1
    
    var body: some View {
        NavigationStack {
            VStack {
                ScrollView([.vertical, .horizontal]) {
                    Image(uiImage: picture ?? UIImage(named: "nopicture")!)
                        .resizable()
                        .scaledToFit()
                        .scaleEffect(getCurrentZoom(magnification: magnification))
                        .gesture(MagnificationGesture()
                            .updating($magnification) { value, state, transaction in
                                state = value
                            }
                            .onEnded { value in
                                zoom = getCurrentZoom(magnification: value)
                            })
                }
            }
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    PhotosPicker(selection: $selected, matching: .images, photoLibrary: .shared()) { Text("Select a Photo") }
                }
            }
            .onChange(of: selected) { item in
                Task(priority: .background) {
                    if let data = try? await item?.loadTransferable(type: Data.self) {
                        picture = UIImage(data: data)
                    }
                }
            }
        }
    }
    func getCurrentZoom(magnification : CGFloat) -> CGFloat {
        let minZoom : CGFloat = 1
        let maxZoom : CGFloat = 4
        var current = zoom * magnification
        current = max(min(current, maxZoom), minZoom)
        return current
    }
}

谢谢