ios - API 不在 Swift for iOS 中显示数据

Question

当前无法从 API 获取数据以进行显示。
当前代码:

import SwiftUI

struct Response: Decodable {
    var content: [Result]
}

struct Result : Decodable {
    var code: String
    var fire: String
    var name: String
    var police: String
    var medical: String
}

struct ContentView: View {
    @State private var content = [Result]()

    var body: some View {
        List(content, id: \.code) { item in
            VStack(alignment: .leading) {
                Text(item.name)
                    .font(.headline)
                Text(item.medical)
            }
        }
        .onAppear(perform: loadData)
    }
    func loadData() {
        
        let url = URL(string: "https://emergency-phone-numbers.herokuapp.com/country/gb")!

        URLSession.shared.dataTask(with: url) { data, response, error in
            if let error = error { print(error); return }
            do {
                let decodedResponse = try JSONDecoder().decode(Response.self, from: data!)
                // we have good data – go back to the main thread
                DispatchQueue.main.async {
                    // update our UI
                    self.content = decodedResponse.content
                }
                
            } catch {
                print(error)
            }
        }.resume()
        
    }
}

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

当前错误:
2021-01-21 19:21:07.094582+0000 iTunes API [39924:1098972] [] nw_protocol_get_quic_image_block_invoke dlopen libquic 失败
keyNotFound(CodingKeys(stringValue: "content", intValue: nil), Swift.DecodingError.Context(codingPath: [], debugDescription: "No value associated with key CodingKeys(stringValue: "content", intValue: nil) ("content")”，底层错误:无))
请指教。提前致谢。

Answer 1

请注意内容来自https://emergency-phone-numbers.herokuapp.com/country/gb是:

{"code":"GB","fire":"999","police":"999","name":"United Kingdom","medical":"999"}

问题是没有 content根据您收到的回复， JSONDecoder无法解析响应。您收到的回复似乎包含适合 Result 的内容，所以如果你改变你的代码来解析它，它工作正常:

import SwiftUI

struct Response: Decodable {
    var content: [Result]
}

struct Result : Decodable {
    var code: String
    var fire: String
    var name: String
    var police: String
    var medical: String
}

struct ContentView: View {
    @State private var content = [Result]()

    var body: some View {
        List(content, id: \.code) { item in
            VStack(alignment: .leading) {
                Text(item.name)
                    .font(.headline)
                Text(item.medical)
            }
        }
        .onAppear(perform: loadData)
    }
    func loadData() {
        
        let url = URL(string: "https://emergency-phone-numbers.herokuapp.com/country/gb")!

        URLSession.shared.dataTask(with: url) { data, response, error in
            if let error = error { print(error); return }
            do {
                let decodedResponse = try JSONDecoder().decode(Result.self, from: data!)
                // we have good data – go back to the main thread
                DispatchQueue.main.async {
                    // update our UI
                    self.content = [decodedResponse]
                }
                
            } catch {
                print(error)
            }
        }.resume()
        
    }
}

我猜，最后，你可能想要一个 Result 的集合。 s 适合 content ，因此您可能需要更改该 API 上的某些内容以返回该集合，然后您的代码将可以正常工作。