onDrop

[JaapWijnen]

Hi! I'm trying to implement dropping files into my macOS app using TCA.
Previously I had the following code attached to a view:

.onDrop(
    of: ["public.file-url"],
    isTargeted: $dragOver,
    perform: { providers in
        providers.first?.loadDataRepresentation(
            forTypeIdentifier: "public.file-url",
            completionHandler: { (data, error) in
                if let data, let path = NSString(data: data, encoding: 4), let url = URL(string: path as String) {
                    let image = NSImage(contentsOf: url)
                    DispatchQueue.main.async {
                        self.image = image
                    }
                }
            }
        )
        return true
    }
)

The isTargeted binding I changed to viewStore.binding(get: \.dragOver, send: LegoPreViewAction.dragOverChanged)
But I'm not sure how to tackle the perform closure and the completion handler within that closure. I was thinking of a viewStore.send(.onDropStarted([NSItemProvider]) action and then handling the logic in the reducer. But I'm not sure how to handle the completion handler from inside the reducer. I should probably do something using environment but not entirely sure how to approach it. Anyone who could point me in the right direction? :)

[JaapWijnen]

For anyone interested! Got it working by making the following environment client:

public struct OnDropImageClient {
    public struct OnDropError: Error, Equatable { }
    
    var onDrop: ([NSItemProvider]) -> Effect<NSImage, OnDropError>
    
    public static let noop = Self(
        onDrop: { _ in .none }
    )
    
    public static let live = Self(
        onDrop: { providers in
            Effect<NSImage, OnDropError>.future { callback in
                providers.first?.loadDataRepresentation(
                    forTypeIdentifier: "public.file-url",
                    completionHandler: { (data, error) in
                        if
                            let data,
                            let path = NSString(data: data, encoding: 4),
                            let url = URL(string: path as String),
                            let image = NSImage(contentsOf: url)
                        {
                            callback(.success(image))
                        }
                        callback(.failure(.init()))
                    }
                )
            }
        }
    )
}

The following modifier on my view:

.onDrop(
    of: ["public.file-url"],
    isTargeted: viewStore.binding(
        get: \.dragOver,
        send: ImageInputAction.dragOverChanged
    ),
    perform: { providers in
        viewStore.send(.onDropImageStarted(providers))
        return true
    }
)

and the following actions in my reducer:

case .dragOverChanged:
    state.dragOver.toggle()
    return .none
    
case .onDropImageStarted(let providers):
    return env.onDropImage.onDrop(providers)
        .receive(on: env.mainQueue)
        .catchToEffect()
        .map(ImageInputAction.onDropImageCompleted)
    
case .onDropImageCompleted(.success(let image)):
    return .none