PostsUI.swift

protocol DataProvider {

  func fetchPosts(withURL url: URL, completion: @escaping (Result<[Post], Error>) -> Void)
    
  func fetchUser(withId id: Int, completion: @escaping (User?) -> Void)
}


struct PostView: View {

  let dataProvider: DataProvider

  init(dataProvider: DataProvider) {
    self.dataProvider = dataProvider
  }

  var body: some View {
    // ...
  }
}