Question

我正在尝试为AlamofireImage的ImageDownloader制作一个小的反应式包装：

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()
        }
    }
}

它编译没有问题。但是，当我尝试在ImageDownloader实例上调用rx.download时，我收到一条错误消息，提示那里没有'rx'扩展名：

有人猜测为什么会这样吗？

Answer 1

您需要先遵守ReactiveCompatible协议，然后才能在downloadRequest调用中使用“ 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()
            }
        }
    }
}

现在您可以像下面一样调用ImageDownloader.default.rx.download(urlRequest:filter:)方法

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)

类型*的值没有成员'rx'

1 个答案: