Value of type * has no member 'rx'

Question

I'm trying to make a small reactive wrapper for ImageDownloader from AlamofireImage:

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()
        }
    }
}

It compiles without a problem. But when I try to call rx.download on an instance of ImageDownloader I get an error saying that there is no 'rx' extension there:

Any guesses why this is happening?

Suhit Patil · Accepted Answer · 2018-12-03T10:14:25.427

You need to conform to ReactiveCompatible protocol first and then you can use 'rx' in your downloadRequest call

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()
            }
        }
    }
}

now you can call ImageDownloader.default.rx.download(urlRequest:filter:) method like below

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)

Update: as of Xcode 11.3, Swift 5 the OP code does not even compile. — Fran Pugl, Dec 16 '19 at 18:00
I pretty much always used types that already conform to that protocol, like `UIView`s. At first I was totally lost with that error, but now it all makes sense. :-) — d4Rk, Aug 24 '20 at 10:56

Value of type * has no member 'rx'

1 Answers1