RxSwift Simple background task example - swift3

Question

I have a method as following
public static func createAlbum(named: String, completion: (album: PHAssetCollection?) -> ()) {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0)) {
}) { success, error in
completion(album: album)
}
}
}
How can i do the background task using RxSwift
complete code
https://gist.github.com/sazzadislam-dsi/d347909d284674c936e397ac423703cf

Answer 1

#XFreire answer is right, but for Swift 3 and RxSwift 3.1.0 I would add an extension to PHAssetCollection:
extension Reactive where Base: PHPhotoLibrary {
func createAlbum(named name: String) -> Observable<PHAssetCollection?> {
return Observable.create { observer in
self.base.performChanges({
// ...
}, completionHandler: { success, error in
if success {
// Your success logic goes here
let album = PHAssetCollection()
// ...
observer.on(.next(album))
observer.on(.completed)
} else if let error = error {
observer.on(.error(error))
} else {
// Your error type
observer.on(.error(MyErrors.Unknown))
}
})
return Disposables.create()
}
}
}
Then you can use the method like this:
PHPhotoLibrary
.shared().rx.createAlbum(named: "MyAlbum")
.subscribe(onNext: { collection in
// ...
}, onError: { error in
// ...
})
.addDisposableTo(disposeBag)

Answer 2

First, your function must return an Observable.
public static func rx_createAlbum(named: String)-> Observable<PHAssetCollection?>
Second, when there is an error, your function will return onError, and when success is true, your function will return onNext(album) and onCompleted().
Code:
public static func rx_createAlbum(named: String)-> Observable<PHAssetCollection?> {
return Observable.create { observer in
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0)) {
// ...
}) { success, error in
if error {
observer.onError(error)
}
else {
var album: PHAssetCollection?
if success {
let collectionFetchResult = PHAssetCollection.fetchAssetCollectionsWithLocalIdentifiers([placeholder?.localIdentifier ?? ""], options: nil)
album = collectionFetchResult.firstObject as? PHAssetCollection
}
observer.onNext(album)
observer.onCompleted()
}
}
}
return Disposables.create()
}
}