類型*的值沒有成員'rx'

Question

我正在嘗試從AlamofireImage為ImageDownloader制作一個小的反應式包裝：

import Foundation
import UIKit.UIImage
import AlamofireImage
import RxCocoa
import RxSwift


extension Reactive where Base: ImageDownloader {

    public func download(urlRequest: URLRequest, filter: ImageFilter?) -> Observable<UIImage> {

        return Observable.create { observer in

            self.base.download(urlRequest, filter: filter) { response in

                if let error = response.error {
                    observer.onError(error)
                } else if let image = response.value {
                    observer.onNext(image)
                }
            }
            return Disposables.create()
        }
    }
}

它編譯沒有問題。 但是，當我嘗試在rx.download實例上調用rx.download時，出現一條錯誤消息，提示那里沒有'rx'擴展名：

任何猜測為什么會這樣？

Answer 1

您需要先遵守ReactiveCompatible協議，然后才能在downloadRequest調用中使用“ rx”

import AlamofireImage
import RxSwift

extension ImageDownloader: ReactiveCompatible {}

extension Reactive where Base: ImageDownloader {

    public func download(urlRequest: URLRequest, filter: ImageFilter?) -> Observable<UIImage> {

        return Observable.create { observer in
            let requestReceipt = ImageDownloader.default.download(urlRequest, filter: filter) { response in
                if let error = response.error {
                    observer.onError(error)
                } else if let image = response.value {
                    observer.onNext(image)
                    observer.onCompleted()
                }
            }
            return Disposables.create {
               requestReceipt?.request.cancel()
            }
        }
    }
}

現在您可以調用ImageDownloader.default.rx.download(urlRequest:filter:)方法，如下所示

let imageRequest = URLRequest.init(url: URL(string: "https://imageserver.com/image/myimage.png")!)
let imageObservable: Observable<UIImage> = ImageDownloader.default.rx.download(urlRequest: imageRequest, filter: nil)