Question 399915 in IOS Swift Question posted in
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Ios swift – Passing argument of non-sendable type 'PhotosPickerItem' outside of main actor-isolated context may introduce data races

My code looks like this and there’s a concurrency warning when accessing the loadTransferable for the selectedPhoto from PhotosPicker

struct SampleCode: View {


    @State var showOptionSheet = false
    @State var showPhotoPicker = false
    @State var selectedPhoto: PhotosPickerItem?
    @State var showProgressView = false

    var body: some View {
        Button {
            showOptionSheet = true
        } label: {
            CustomAvatar(
                imageURL: guestProfile.avatarUrl,
                width: 40,
                height: 40
            )

        }.confirmationDialog("Upload new Avatar", isPresented: $showOptionSheet, titleVisibility: .visible, actions: {
            Button {
                showPhotoPicker = true
            } label: {
                Text("Photos Library")
            }

        })
        .photosPicker(isPresented: $showPhotoPicker, selection: $selectedPhoto, matching: .images)
        .task(id: selectedPhoto) {
            showProgressView = true
            if let data = try? await selectedPhoto?.loadTransferable(type: Data.self) { // WARNING: Passing argument of non-sendable type 'PhotosPickerItem' outside of main actor-isolated context may introduce data races
                let result = await uploadUserAvatar(data: data)
                if let result {
                    guestProfile.avatarUrl = result
                }
            }
            showProgressView = false
        }
    }


}

We recently set the concurrency warnings to complete and I’m not really sure what to do with this

I tried to make PhotosPickerItem conform to Sendable but it produces a different warning and I’m not sure if this is safe

extension PhotosPickerItem: Sendable {} // Conformance to 'Sendable' must occur in the same source file as struct 'PhotosPickerItem'; use '@unchecked Sendable' for retroactive conformance

What’s the best way to solve this?

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2

Answers


  1. 0

    This will work if you move the code inside a .onChange modifier instead and use Task

    .onChange(of: selectedPhoto) { _, photo in
    Task {
        showProgressView = true
        if let data = try? await photo?.loadTransferable(type: Data.self) { 
            let result = await uploadUserAvatar(data: data)
            if let result {
                guestProfile.avatarUrl = result
            }
        }
        showProgressView = false
    }
}

    Here we don’t pass selectedPhoto outside the main actor instead we have a constant local variable photo that we pass to the task.

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  2. 0

    You can tell your task view modifier to use its own copy of selectedPhoto with a capture list:

    .task(id: selectedPhoto) { [selectedPhoto] in                  // note the capture list
    showProgressView = true
    if let data = try? await selectedPhoto?.loadTransferable(type: Data.self) {
        …
    }
    showProgressView = false
}
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