Why does the .png file I export from View(SwiftUI) not contain the ImageView?

This is a macOS app, while using Image("my file url") in my CoverImageView, I can export a .png file that contains the Image("my file url") view successfully.

However, this doesn't happen when I use Image(nsImage: NSImage(data: imageData.imagedata)), the imageData.imagedata is a Data type that will be gotten when I tap a button and get it from a selected picture (I will show it later in my code).

When I select an image, it can be seen in my app's View.

However, when I save this View(CoverImageView) to a .png file it only contain the blue view, the Mac view is gone!!!!

Here is the CoverImageView from which I want to create a .png file

struct CoverImageView: View {
    
    @EnvironmentObject var imageData: ImageData
    
    var body: some View {
        ZStack {
            Rectangle()
                .frame(width: 512, height: 600)
                .foregroundColor(.blue)
            
            Image(nsImage: (NSImage(data: imageData.imagedata) ?? NSImage(byReferencing: URL(fileURLWithPath: ""))))
                .resizable()
                .aspectRatio(contentMode: .fit)
                .frame(width: 512, height: 512)
        }
    }
}

This is the main view PhotoTestView

struct PhotoTestView: View {
    
    @State private var imageUrl: URL = URL(fileURLWithPath: "")
    
    @EnvironmentObject var imageData: ImageData
    
    var body: some View {
        VStack {
            CoverImageView()
            
            Divider()
                .frame(width: 1024)
            
            HStack {
                Button(action: {
                    if let openURL = ImageProcess().showOpenPanel() {
                        imageUrl = openURL
                        if let codedImages = try? Data(contentsOf: openURL) {
                            imageData.imagedata = codedImages
                        }
                    }
                }, label: {
                    Image(systemName: "doc.badge.plus")
                })
                
                Button(action: {
                    ImageProcess().saveImage()
                }, label: {
                    Image(systemName: "square.and.arrow.down")
                })
            }.padding()
        }
    }
}

The View Extension which will create a png file from a view

extension View {
    func imageRepresentation(rect: CGRect) -> NSBitmapImageRep? {
        let hosting = NSHostingView(rootView: self)
        hosting.setFrameSize(rect.size)
        hosting.setBoundsSize(rect.size)
        hosting.layout()
        hosting.layerContentsRedrawPolicy = .onSetNeedsDisplay
        hosting.setNeedsDisplay(rect)
        if let imageRepresentation = hosting.bitmapImageRepForCachingDisplay(in: rect) {
            hosting.cacheDisplay(in: rect, to: imageRepresentation)
            return imageRepresentation
        }
        return nil
    }
    
    func asImage(rect: CGRect) -> NSImage? {
        if let cgImage = imageRepresentation(rect: rect)?.cgImage {
            return NSImage(cgImage: cgImage, size: rect.size)
        }
        return nil
    }
    
    func asPngData(rect: CGRect) -> Data? {
        return imageRepresentation(rect: rect)?.representation(using: .png, properties: [:])
    }
}

png File Reader and Save

struct ImageProcess {
    func showOpenPanel() -> URL? {
        let openPanel = NSOpenPanel()
        openPanel.allowedContentTypes = [.image]
        openPanel.allowsMultipleSelection = false
        openPanel.canChooseDirectories = false
        openPanel.canChooseFiles = true
        let response = openPanel.runModal()
        return response == .OK ? openPanel.url : nil
    }
    
    
    func saveURL() -> URL? {
        let savePanel = NSSavePanel()
        savePanel.allowedContentTypes = [.png]
        savePanel.canCreateDirectories = true
        savePanel.isExtensionHidden = false
        savePanel.allowsOtherFileTypes = false
        savePanel.title = "Save your image"
        savePanel.message = "Choose a folder and a name to store your image."
        savePanel.nameFieldLabel = "File name:"
        let response = savePanel.runModal()
        return response == .OK ? savePanel.url : nil
    }
    
    func saveImage() {
        let view = CoverImageView().environmentObject(ImageData())
        let imageData = view.asPngData(rect: CGRect.init(x: 0, y: 0, width: 1024, height: 768))
        if let url = saveURL() {
            try? imageData!.write(to: url)
        }
         // print(imageData)
    }
}

Could you help me?