result with combine 得不到结果

Question

我写的一切都是正确的，代码本身也能正常工作，但它给了我一个错误调用 'fetchPokemon()' 的结果未使用，这里可能是什么问题？

听到的是我的代码：ModelView class

 import Foundation
 import Combine
 class NetworkManager: ObservableObject {

let baseuRL = "https://pokeapi.co/api/v2/pokemon"

@Published var pokemon: [Pokemon] = []
var error: Error?
var cancellables: Set<AnyCancellable> = []

func fetchPokemon() -> Future<[Pokemon], Error> {
    return Future<[Pokemon], Error> { promice in
        guard let url = URL(string: "\(self.baseuRL)") else {
            return promice(.failure(ApiError.unknowed))
        }
        URLSession.shared.dataTaskPublisher(for: url)
            .tryMap { (data, response) -> Data in
                guard let http = response as? HTTPURLResponse,
                      http.statusCode == 200 else {
                    throw ApiError.responseError
                }
                return data
            }
            .decode(type: PokemonList.self, decoder: JSONDecoder())
            .receive(on: RunLoop.main)
            .sink(receiveCompletion: { completion in
                switch completion {
                case .finished:
                    break
                case .failure(let error):
                    print(error)
                }
            }, receiveValue: {
                promice(.success([=10=].results))
            })
            .store(in: &self.cancellables)
    }
}


 struct ContentView: View {
@StateObject var net = NetworkManager()
var body: some View {
    List(net.pokemon, id: \.self) { pokemon in
        Text(pokemon.name)
    }.onAppear {
        net.fetchPokemon()
    }
}

}

Answer 1

你的 fetchPokemon 函数 returns a Future，但你没有对它做任何事情——这就是你得到未使用错误的原因。

此外，在该函数中，您将返回您的承诺，但不会对结果做任何事情。因此，您需要处理 Future 并对这些结果进行处理。

它可能类似于以下内容：


class NetworkManager: ObservableObject {
    
    let baseuRL = "https://pokeapi.co/api/v2/pokemon"
    
    @Published var pokemon: [Pokemon] = []
    var error: Error?
    var cancellables: Set<AnyCancellable> = []
    
    //New function here:
    func runFetch() {
        fetchPokemon().sink { (completion) in
            //handle completion, error
        } receiveValue: { (pokemon) in
            self.pokemon = pokemon //do something with the results from your promise
        }.store(in: &cancellables)
    }
    
    private func fetchPokemon() -> Future<[Pokemon], Error> {
        return Future<[Pokemon], Error> { promice in
            guard let url = URL(string: "\(self.baseuRL)") else {
                return promice(.failure(ApiError.unknowed))
            }
            URLSession.shared.dataTaskPublisher(for: url)
                .tryMap { (data, response) -> Data in
                    guard let http = response as? HTTPURLResponse,
                          http.statusCode == 200 else {
                        throw ApiError.responseError
                    }
                    return data
                }
                .decode(type: PokemonList.self, decoder: JSONDecoder())
                .receive(on: RunLoop.main)
                .sink(receiveCompletion: { completion in
                    switch completion {
                    case .finished:
                        break
                    case .failure(let error):
                        print(error)
                    }
                }, receiveValue: {
                    promice(.success([=10=].results))
                })
                .store(in: &self.cancellables)
        }
    }
}


struct ContentView: View {
    @StateObject var net = NetworkManager()
    var body: some View {
        List(net.pokemon, id: \.self) { pokemon in
            Text(pokemon.name)
        }.onAppear {
            net.runFetch() //call runFetch instead of fetchPokemon
        }
    }
}

由于您没有包含 PokemonList 的代码，我对其内容做了一个假设：

struct PokemonList: Codable {
    var results: [Pokemon]
}

如果类型不同，您必须在 runFetch 中更改 receiveValue 中发生的情况。

result with combine 得不到结果

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