How to handle ShareLink in SwiftUI - I get memory leaks when I update an image?

Question

I'll try to explain this as simple as possible. I've made an app that modifies an UIImage based on user actions.

To be able to share/save the resulting image, I added a ShareLink to my view.

Every time the user makes changes to the image the app consumes memory which is never released.

When I remove the ShareLink() the memory is released and works as expected.

Have I missed something regarding how ShareLink() works? I have read the Apple documentation, but I don't get any wiser.

Btw, I am using a @State-variable for my controller, which should be ok since it's not an ObservableObject.

This is the basic structure of my app, very simplified.

class ImageController() {
  func modifyImage(photo: UIImage?) -> async UIImage? {
    // do stuff here

    return resultingUIImage
  }
}

struct ContentView: View {
  @State private var photo: UIImage?
  @State private var imageController: ImageController()

  var body: some View {
    VStack {
      Image(uiImage: photo)

      HStack {
        Button("Modify the image") {
          Task {
            let newPhoto = await modifyImage(photo)
 
            DispatchQueue.main.async {
              self.photo = newPhoto
            }
          }
        }
        // when removing ShareLink() below the app doesn't leak memory
        ShareLink(item: Image(uiImage: photo), preview: SharePreview("Description", image: Image(uiImage: photo))
      }
    }
  }
}

Answer 1

I have now solved it, but not sure if it's the correct way. This is what I did:

1. Create a a sharable object:

struct ShareableJpeg {
    let imageData: Data
}

extension ShareableJpeg: Transferable {
    enum ShareError: Error {
        case failed
    }
    
    static var transferRepresentation: some TransferRepresentation {
        DataRepresentation(exportedContentType: .jpeg) { object in
            return object.imageData
        }
    }
}

2. Create a state variable holding the image:

@State var shareableJpeg: ShareableJpeg?

3. Implement ShareLink():

ShareLink(item: shareableJpeg, preview: SharePreview("Description", image: Image("AppIcon"))) {
  Label("Share", systemImage: "square.and.arrow.up")
}

4. Assigning the shareableJpeg:

let resultingImage = await imageController.applyStuff(image)

if let jpegData = image.jpegData(compressionQuality: 0.9) {
    shareableJpeg = ShareableJpeg(imageData: jpegData)
}