RxSwift: tap a button to do a request with Alamofire, how to make it work?

Question

I have some UI rx button tap, I want to connect it to the network rx part.

Here is Rx btn tap part:

btn.rx.tap.take(1).flatMap {  [unowned self]  () -> Observable<Bool>  in
            // ...
            return NetManager.standard.request()
        }.debug().do(onNext: { _ in
                print("The data flows here")
            }).flatMapLatest { (echo: Bool) -> Observable<Bool> in
            if echo{
                if let app = UIApplication.shared.delegate as? AppDelegate{
                    app.goHome()
                }
                return Observable.of(true)
            }
            else{
                return Observable.of(false)
            }
        }.subscribe(onNext: { (result) in
            // ... , do sth with result
        }).disposed(by: rx.disposeBag)

Here is net request part with Alamofire:

class NetManager: NSObject {
    
    static let standard = NetManager()
    var dataRequest: DataRequest?
    
    func request() -> Observable<Bool> {
           return Observable<Bool>.create{ (observer) -> Disposable in
                    let data = // ...
                    // ...
                    self.dataRequest = AF.request(aURL, method: HTTPMethod.post, parameters: data, encoder: JSONParameterEncoder.prettyPrinted, headers: aHead).response { (response: DataResponse<Data?>) in
                            self.hud?.hide()
                           if let data = response.data{
                               observer.onNext(true)
                                // ....
                           }
                           else{
                               observer.onNext(false)
                           }
                       }
                    observer.onCompleted()
                    return Disposables.create{}
           }
       }
    
}

Here is the debug info:

Controller.swift:141 (viewDidLoad()) -> subscribed

Controller.swift:141 (viewDidLoad()) -> Event completed

Controller.swift:141 (viewDidLoad()) -> isDisposed

The result is, the do( next ) part seems like that it has not been called. Because no print in console.

---

The question is, how to make the rx logic work?

---

Here is what I tried:

turn btn.rx.tap.flatMap to btn.rx.tap.take(1).flatMap

because from this issue

if a flatMap completion would terminate the outer stream, it would mean that no more button taps would be registered in your stream, which don't really make sense.

---

Seen from this question

  btn.rx.tap.map { () -> Observable<Bool> in

    return NetManager.standard.request()
  }.flatMapLatest { (observer: Observable<Bool>) -> Observable<Bool> in
  
    // of cource, I can subscribe to observer
    /*
     observer.subscribe(onNext: { (echo) in
         
     })
     */
    
    
    // how to get the event element elegantly.
    
    return Observable.of(false)
}.subscribe(onNext: { (_) in
    
}).disposed(by: rx.disposeBag)

how to do this more elegantly.

Answer 1

The main issue here is that when performing the network request, you are not waiting for the network call to respond. So observer.onComplete() is triggered before observer.onNext()

class NetManager: NSObject {

static let standard = NetManager()
var dataRequest: DataRequest?

func request() -> Observable<Bool> {
       return Observable<Bool>.create { (observer) -> Disposable in
                let data = // ...
                // ...
                self.dataRequest = AF.request(aURL, method: HTTPMethod.post, parameters: data, encoder: JSONParameterEncoder.prettyPrinted, headers: aHead).response { (response: DataResponse<Data?>) in
                        self.hud?.hide()
                       if let data = response.data {
                           observer.onNext(true)
                           // ... 
                       }
                       else {
                           observer.onNext(false)
                       }
                       observer.onComplete() // Moving it here instead will wait for the response
                }
                return Disposables.create { }
       }
   }
}

At this point, your code should work as it is, but you're still overcomplicating a very simple thing.

Here is what to do:

btn.rx.tap
    .flatMap { _ in
        return NetManager.standard.request()
    }
    .subscribe(onNext: { (success) in
        if success {
            if let app = UIApplication.shared.delegate as? AppDelegate {
                app.goHome()
            }
        } 
    })
    .disposed(by: rx.disposeBag)