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IOS11 file provider startProvidingItem not called

I am using the file provider extension for iOS 11.

Despite the conference at https://developer.apple.com/videos/play/wwdc2017/243/ and Apple Documentation navigation, I still cannot figure out how to implement some of the methods for the NSFileProviderExtension and NSFileProviderEnumerator objects.

I have successfully implemented NSFileProviderItem, having all of the Navite iOS 11 Files listed in the application. However, when I select a file, I cannot start the application based on the document.

I redefined all methods for NSFileProviderExtension. Some of them are still empty, but I set a checkpoint to check when they are called.

NSFileProviderExtension looks something like this:

class FileProviderExtension: NSFileProviderExtension {
    var db : [FileProviderItem]  = [] //Used "as" a database
...

    override func item(for identifier: NSFileProviderItemIdentifier) throws -> NSFileProviderItem {
        for i in db {
            if i.itemIdentifier.rawValue == identifier.rawValue {
                return i
            }
        }
        throw NSError(domain: NSCocoaErrorDomain, code: NSNotFound, userInfo:[:])
    }

    override func urlForItem(withPersistentIdentifier identifier: NSFileProviderItemIdentifier) -> URL? {
        guard let item = try? item(for: identifier) else {
            return nil
        }

        // in this implementation, all paths are structured as <base storage directory>/<item identifier>/<item file name>
        let manager = NSFileProviderManager.default
        let perItemDirectory = manager.documentStorageURL.appendingPathComponent(identifier.rawValue, isDirectory: true)

        return perItemDirectory.appendingPathComponent(item.filename, isDirectory:false)
    }

    // MARK: - Enumeration
    func enumerator(for containerItemIdentifier: NSFileProviderItemIdentifier) throws -> NSFileProviderEnumerator {
        var maybeEnumerator: NSFileProviderEnumerator? = nil

        if (containerItemIdentifier == NSFileProviderItemIdentifier.rootContainer) {
            maybeEnumerator = FileProviderEnumerator(enumeratedItemIdentifier: containerItemIdentifier)
            self.db = CustomData.getData(pid: containerItemIdentifier)

        } else if (containerItemIdentifier == NSFileProviderItemIdentifier.workingSet) {
            // TODO: instantiate an enumerator for the working set
        } else {

        }
        guard let enumerator = maybeEnumerator else {
            throw NSError(domain: NSCocoaErrorDomain, code: NSFeatureUnsupportedError, userInfo:[:])
        }
        return enumerator
    }

My enumerateItems looks something like this:

class FileProviderEnumerator: NSObject, NSFileProviderEnumerator {

    override func enumerateItems(for observer: NSFileProviderEnumerationObserver, startingAt page: NSFileProviderPage) {

        let itens = CustomData.getData(pid: enumeratedItemIdentifier)
        observer.didEnumerate(itens)
        observer.finishEnumerating(upTo: nil)

    }

CustomData.getData. NSFileProviderItem . , .

class CustomData {


    static func getData(pid : NSFileProviderItemIdentifier) -> [FileProviderItem] {
        return [
            FileProviderItem(uid: "0", pid: pid, name: "garden", remoteUrl : "https://img2.10bestmedia.com/Images/Photos/338373/GettyImages-516844708_54_990x660.jpg"),
            FileProviderItem(uid: "1", pid: pid, name: "car", remoteUrl : "https://static.pexels.com/photos/170811/pexels-photo-170811.jpeg"),
            FileProviderItem(uid: "2", pid: pid, name: "cat", remoteUrl : "http://www.petmd.com/sites/default/files/what-does-it-mean-when-cat-wags-tail.jpg"),
            FileProviderItem(uid: "3", pid: pid, name: "computer", remoteUrl : "http://mrslamarche.com/wp-content/uploads/2016/08/dell-xps-laptop-620.jpg")
        ]
    }

}

, , urlForItem , URL- .

? .

-nls

+4
2

, makePlaceholder ( url:).

.

-nls

EDIT:

, (:). containerItemIdentifier, " ". NSFileProviderEnumerator, .

, (:) :

class FileProviderExtension: NSFileProviderExtension {

    override func enumerator(for containerItemIdentifier: NSFileProviderItemIdentifier) throws -> NSFileProviderEnumerator {

        var enumerator: NSFileProviderEnumerator? = nil

        if (containerItemIdentifier == NSFileProviderItemIdentifier.rootContainer) {
            enumerator = FileProviderEnumerator(enumeratedItemIdentifier: containerItemIdentifier)
        }
        else {
            enumerator = FileProviderEnumerator(enumeratedItemIdentifier: containerItemIdentifier)
        }
        if enumerator == nill {
            throw NSError(domain: NSCocoaErrorDomain, code: NSFeatureUnsupportedError, userInfo:[:])
        }
        return enumerator
    }

    (...)

}

, , FileProviderEnumerator . enumerateItems ( observer:, startAt page:)

:

class FileProviderEnumerator: NSObject, NSFileProviderEnumerator {

    func enumerateItems(for observer: NSFileProviderEnumerationObserver, startingAt page: NSFileProviderPage) { 

        if (enumeratedItemIdentifier == NSFileProviderItemIdentifier.rootContainer) {

            //Creating an example of a folder item
            let folderItem = FileProviderFolder()
            folderItem.parentItemIdentifier = enumeratedItemIdentifier  //<-- Very important
            folderItem.typeIdentifier = "public.folder"
            folderItem.name = "ExampleFolder"
            folderItem.id = "ExampleFolderID"

            //Creating an example of a file item
            let fileItem = FileProviderFile()
            fileItem.parentItemIdentifier = enumeratedItemIdentifier    //<-- Very important
            fileItem.typeIdentifier = "public.plain-text"
            fileItem.name = "ExampleFile.txt"
            fileItem.id = "ExampleFileID"


            self.itemList.append(contentsOf: [folderItem, fileItem])
            observer.didEnumerate(self.itemList)
            observer.finishEnumerating(upTo: nil)

        }
        else {
            //1 > Find directory name using "enumeratedItemIdentifier" property
            //2 > Fetch data from the desired directory
            //3 > Create File or Folder Items 
            //4 > Send items back using didEnumerate and finishEnumerating
        }
    }

    (...)

}

, FileProviderEnumerators, containerItemIdentifier. , .

: , parentItemIdentifier. , , . , , typeIdentifier (UTI) .

, , , NSFileProviderItem. File Folder typeIdentifier. :

class FileProviderFolder: NSObject, NSFileProviderItem {

    public var id: String?
    public var name: String?

    var parentItemIdentifier: NSFileProviderItemIdentifier
    var typeIdentifier: String

    init() {

    }

    var itemIdentifier: NSFileProviderItemIdentifier {
        return NSFileProviderItemIdentifier(self.id!)
    }

    var filename: String {
        return self.name!
    }
}

ItemIdentifier , , , (. enumerator (:)).

EDIT2

, startProvidingItem ( url:). 3 :

1 - ( URL-, )

2 - , URL-. Alamofire ;

3 - Handler;

:

class FileProviderExtension: NSFileProviderExtension {


    override func urlForItem(withPersistentIdentifier identifier: NSFileProviderItemIdentifier) -> URL? {
        // resolve the given identifier to a file on disk
        guard let item = try? item(for: identifier) else {
            return nil
        }
        // in this implementation, all paths are structured as <base storage directory>/<item identifier>/<item file name>
        let perItemDirectory = NSFileProviderManager.default.documentStorageURL.appendingPathComponent(identifier.rawValue, isDirectory: true)
        let allDir = perItemDirectory.appendingPathComponent(item.filename, isDirectory:false)
        return allDir
    }

    override func persistentIdentifierForItem(at url: URL) -> NSFileProviderItemIdentifier? { 
        // exploit that the path structure has been defined as <base storage directory>/<item identifier>/<item file name>, at urlForItem
        let pathComponents = url.pathComponents
        assert(pathComponents.count > 2)
        return NSFileProviderItemIdentifier(pathComponents[pathComponents.count - 2])
    }

    override func startProvidingItem(at url: URL, completionHandler: @escaping (Error?) -> Void) {

        guard
            let itemID = persistentIdentifierForItem(at: url),
            let item = try? self.item(for: itemID) as! FileProviderFile else {
                return
        }

        DownloadfileAsync(
            file: item,
            toLocalDirectory: url,
            success: { (response) in

                // Do necessary processing on the FileProviderFile object
                // Example: setting isOffline flag to True

                completionHandler(nil)
            },
            fail: { (response) in
                completionHandler(NSFileProviderError(.serverUnreachable))
            }
        )

    }

    (...)
}

, URL- : URL- .

URL- urlForItem.

, .

-nls

+3

, , - . startProvidingItem , , , :

<Your container path>/File Provider Storage/<itemIdentifier>/My Awesome Image.png

WWDC17 FileProvider, , .

, " ", , startProvidingItem . , FileID, , " ", startProvidingItem.

, iOS11 Placeholder, FileProviderExtension, , , , , .

+1

Source: https://habr.com/ru/post/1687297/

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