RxSwift subscribe block not called

4
votes

I'm playing around with RxSwift and I'm stuck with a simple toy programm. My program essentially contains a model class and a viewcontroller. The model contains an observable that gets updated on the main queue after an asynchronous network call, the viewcontroller subscribes in viewDidLoad(). The AppDelegate initializes the model and passes it to ViewController and triggers the network request.

class GalleryModel {

    var galleryCount: BehaviorSubject<Int>

    init() {
        galleryCount = BehaviorSubject.init(value:0)
    }

    func refresh() {
         doAsyncRequestToAmazonWithCompletion { (response) -> AnyObject! in
             var counter = 0
             //process response
             counter = 12

             dispatch_async(dispatch_get_main_queue()) {
                self.galleryCount.on(.Next(counter))
             }
             return nil
        }
    }

class ViewController: UIViewController {

    @IBOutlet weak var label: UILabel!

    var galleryModel: GalleryModel?

    override func viewDidLoad() {
        super.viewDidLoad()
        galleryModel?.galleryCount.subscribe { e in
            if let gc = e.element {
               self.label.text = String(gc)
            }
        }
   }
}

class AppDelegate: UIResponder, UIApplicationDelegate {
    var galleryModel: GalleryModel?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {        
        //do amazon setup        
        galleryModel = GalleryModel()
        if let viewController = window?.rootViewController as? ViewController {
            viewController.galleryModel = GalleryModel()
        }    
        return true
    }

    func applicationDidBecomeActive(application: UIApplication) {
        galleryModel?.refresh()
    }

The label gets updated only one, it shows "0". I expected the label to get updated twice, showing "0" after the first update and showing "12" after the second update after the processing of the network request. A breakpoint in the dispatch_async block gets hit, but it seems that galleryCount lost its observer. Anybody any idea what's happening or how to debug this?

Best

3
iosswiftrx-swift
Can you confirm that the On Next in GalleryModel is getting called? – Eric
The thing/problem is how RxSwift is written, I mean, once .on(.Error()) is called, it removes the observer and there is not way to call .on(.Next()) again. The only way to do this is creating a new instance of the viewModel and call subscribe again. I really hate this library {>_<} – eMdOS

3 Answers

3
votes

In case reads this anyone is interested. It was an refactoring error, after renaming variables I stopped passing the observable to the ViewController. Instead I created a new one... facepalm

0
votes

Here are some useful snippets for subscribe in RxSwift (in Japanese)

For example to subscribe to different events:

let source: Observable<Int> = create { (observer: ObserverOf<Int>) in
    sendNext(observer, 42)
    sendCompleted(observer)
    return AnonymousDisposable {
        print("disposed")
    }
}

let subscription = source.subscribe { (event: Event<Int>) -> Void in
    switch event {
    case .Next(let element):
        print("Next: \(element)")
    case .Completed:
        print("Completed")
    case .Error(let error):
        print("Error: \(error)")
    }
}
0
votes

Clean and Build solved the problems for me