RxSwift 等待 observable 完成，然后返回 observable

Question

当我使用 loadMovies 函数时，只有在 ViewController 调用函数并处理它之后才能获得所需的电影，这个函数在 API 中

func loadMovies() -> Observable<[Movie]> {
    let obsMovies = self.APICall(genrePath: Movies.action, structType: Movie.self)
    return Observable.create{ observer -> Disposable in
        obsMovies.subscribe(
            onNext: { element in 
                      observer.onNext(element)
                      print(element) 
           }
        )
        observer.onCompleted()
        return Disposables.create()
    }
}

在 ViewController 中，我在 viewDidLoad 中调用这个函数

request.api.loadMovies()
    .debug()
    .subscribe(
        onNext:{ data in
            do {
                print(data)
            }
        },
        onError: { error in
            print(error)
        },
        onCompleted: {
            print("Completed")
        },
        onDisposed: {
            print("Disposed")
        }
    )
    .disposed(by: disposeBag)

得到这个输出

ViewController.swift:55 (viewDidLoad()) -> subscribed
ViewController.swift:55 (viewDidLoad()) -> Event completed
Completed
Disposed
ViewController.swift:55 (viewDidLoad()) -> isDisposed

[MovieTest.Movie(name: "Black Panther", year: "2018", rating: "83")]
[MovieTest.Movie(name: "AVENGERS: ENDGAME", year: "2019", rating: "90")]
[MovieTest.Movie(name: "MISSION: IMPOSSIBLE -- FALLOUT", year: "2018", rating: "88")]...

我想知道如何在处理之前等待函数获取电影。我想在 tableView 中显示所有内容。我是 RxSwift 的初学者，我相信有更好的方法来实现这一点，但目前我不知道。谢谢

Answer 1

所以有几个问题需要立即解决...obsMovies.subscribe() 返回一个您忽略的一次性用品。由于它嵌入的闭包需要返回一个一次性的，所以只返回一个订阅创建的而不是创建一个新的：

func loadMovies() -> Observable<[Movie]> {
    let obsMovies = self.APICall(genrePath: Movies.action, structType: Movie.self)
    return Observable.create{ observer -> Disposable in
        let disposable = obsMovies.subscribe(
            onNext: { element in
                observer.onNext(element)
                print(element)
            }
        )
        observer.onCompleted()
        return disposable
    }
}

接下来，请注意 APICall(genrePath:structType:) 返回一个 Observable<[Movie]> 那么为什么不直接返回它而不是将其包装在另一个 Observable 中呢？

func loadMovies() -> Observable<[Movie]> {
    return self.APICall(genrePath: Movies.action, structType: Movie.self)
}

哇，现在我有点想知道为什么loadMovies() 存在...?

现在我已经完成了上述操作，这是我看到的输出：

ViewController.swift:55 (viewDidLoad()) -> subscribed
ViewController.swift:55 (viewDidLoad()) -> Event next([MovieTest.Movie(name: "Black Panther", year: "2018", rating: "83"), MovieTest.Movie(name: "AVENGERS: ENDGAME", year: "2019", rating: "90"), MovieTest.Movie(name: "MISSION: IMPOSSIBLE -- FALLOUT", year: "2018", rating: "88")])
[MovieTest.Movie(name: "Black Panther", year: "2018", rating: "83"), MovieTest.Movie(name: "AVENGERS: ENDGAME", year: "2019", rating: "90"), MovieTest.Movie(name: "MISSION: IMPOSSIBLE -- FALLOUT", year: "2018", rating: "88")]
ViewController.swift:55 (viewDidLoad()) -> Event completed
Completed
Disposed
2021-04-11 20:05:08.356: Stuff.swift:55 (viewDidLoad()) -> isDisposed