Bring desktop class sync to iOS with FileProvider

6:04 - Implement a Progress Cancellation Handler

// Implementing a progress cancellation handler

public func modifyItem(_ item: ..., completionHandler: (..., Error?) -> Void) -> Progress {
    let progress = Progress()
    let uploadTask = Task {
        do {
            // ...
            try Task.checkCancellation()
            // ...
        } catch let error {
            completionHandler(nil, [], false, error)
        }
    }

    progress.cancellationHandler = {
        uploadTask.cancel()
    }
    return progress
}

6:53 - Register for Push Notifications

// Registering for push notifications

import PushKit

let pushRegistry = PKPushRegistry(queue: queue)

pushRegistry.delegate = self
pushRegistry.desiredPushTypes = Set([PKPushType.fileProvider])

...

// On the server: push
//
// {
//    "container-identifier" = "NSFileProviderWorkingSetContainerItemIdentifier"
//    "domain" = "<domain identifier>"
// }
//
// with topic "<your application identifier>.pushkit.fileprovider"

8:53 - Drag and Drop: Implement Dragging

// Sending out drags

var body: some View {
    Text("🥐")
    .onDrag {
        let itemProvider = NSItemProvider()
        itemProvider.registerFileRepresentation(for: .folder,
                                                openInPlace: true) { completionHandler in
            self.manager.getUserVisibleURL(for: folderItemID) { fileURL, error in
                guard let fileURL = fileURL else {
                    completionHandler(nil, false, error)
                    return
                }
                completionHandler(fileURL, true, nil)
            }
            return Progress()  
        }
        return itemProvider
    }
}

9:24 - Drag and Drop: Implement Dropping

// Receiving drops

var body: some View {
    Text("🥬")
    .onDrop(of: [.folder], isTargeted: $dropTarget) { providers in
        guard let prov = providers.first(where: { provider in
            !provider.registeredContentTypes(conformingTo: .folder).isEmpty
        }) else {
            return false
        }
        prov.loadFileRepresentation(for: .folder, openInPlace: true) { url, inPlace, err in
            guard let url = url else { return }
            Task {
                url.startAccessingSecurityScopedResource()
                // use URL
                url.stopAccessingSecurityScopedResource()
            }
        }
        return true
    }
}