值：(failure(Alamofire.AFError.explicitlyCancelled)) 使用 Alamofire 发布者时

Question

I;m learning SwiftUI and Alamofire. I created a demo APP like this:

import SwiftUI

import Alamofire

struct ContentView: View {
    var body: some View {
        Text("Hello, world!")
            .padding()
            .onAppear(perform: load)
    }
    
    struct TestResponse: Decodable {
        let userId: Int
        let id: Int
        let title: String
        let body: String
    }
    
    func load(){
        AF.request("https://jsonplaceholder.typicode.com/posts", method: .get, parameters: nil)
            .validate()
            .publishDecodable(type: [TestResponse].self)
            .print()
            .sink { print($0) }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

But I got this output:

receive subscription: (Alamofire.DataResponsePublisher<Swift.Array<Test.ContentView.TestResponse>>.(unknown context at $1080f8314).Inner<Combine.Publishers.Print<Alamofire.DataResponsePublisher<Swift.Array<Test.ContentView.TestResponse>>>.(unknown context at $7ff81332d748).Inner<Combine.Subscribers.Sink<Alamofire.DataResponse<Swift.Array<Test.ContentView.TestResponse>, Alamofire.AFError>, Swift.Never>>>)
request unlimited
receive cancel
receive value: (failure(Alamofire.AFError.explicitlyCancelled))
receive finished

if I use the .response to receive the data, everything is ok.

Thanks for any help.

Answer 1

You need to store the token returned by sink (which you're likely getting a compiler warning about). Otherwise the publisher you created is immediately cancelled and the underlying request is cancelled as well. You can use a Set<AnyCancellable> to and sink {}.store(in: &set) , or find an alternate solution. For SwiftUI you'll likely want to put your networking in some sort of model object, not the view.