class Network {
    func getingData(completion : @escaping ([Model]) -> ()) async {
        guard let url = URL(string: "https://jsonplaceholder.typicode.com/posts") else { return }
        do {
            let (data, _) = try await URLSession.shared.data(from: url)
            if let posts = try? JSONDecoder().decode([Model].self, from: data) {
                completion(posts)
            }
        }
        catch {
            print("error")
        }
    }
}

CodePudding user response：

You could try something like this approach, where getData works with Decodable, as was mentioned in the previous answer. In this particular example an array of Decodable.

struct Post: Decodable, Identifiable {
    let userId: Int
    let id: Int
    let title: String
    let body: String
    var comments: [Comment]?
}

struct Comment: Decodable, Identifiable {
    let postId: Int
    let id: Int
    let name: String
    let email: String
    let body: String
}

struct ContentView: View {
    let client = Network()
    @State var posts: [Post] = []  
    
    var body: some View {
        List {
            ForEach(posts, id: \.id) { post in
                Text(post.title)
            }
        }
        .task {
            posts = await client.getData(from: "https://jsonplaceholder.typicode.com/posts")
            // all comments from the first post
            let comments: [Comment] = await client.getData(from: "https://jsonplaceholder.typicode.com/posts/\(posts[0].id)/comments")
            print("\n---> comments: \(comments)")
        }
    }
}

class Network {

    func getData<T: Decodable>(from urlString: String) async -> [T] {
        guard let url = URL(string: urlString) else {
            print(URLError(.badURL))
            return [] // <-- todo, deal with errors
        }
        do {
            let (data, response) = try await URLSession.shared.data(for: URLRequest(url: url))
            guard let httpResponse = response as? HTTPURLResponse, httpResponse.statusCode == 200 else {
                print(URLError(.badServerResponse))
                return [] // <-- todo, deal with errors
            }
            let results = try JSONDecoder().decode([T].self, from: data)
            return results
        }
        catch {
            return [] // <-- todo, deal with errors
        }
    }
    
}

CodePudding user response：

Is it what you're looking for?

import Foundation

class Network {

  func getingData<Model: Decodable>(completion : @escaping ([Model]) -> ()) async {
    guard let url = URL(string: "https://jsonplaceholder.typicode.com/posts") else {
      return
    }
    do {
      let (data, _) = try await URLSession.shared.data(from: url)
      if let posts = try? JSONDecoder().decode([Model].self, from: data) {
        completion(posts)
      }
    } catch {
      print("error")
    }
  }

}

If so, you only need to declare the Model type as generic. The only thing you need Model to conform is Decodable (the requirement of the JSONDecoder().decode([Model].self, from: data) call).