如何在swiftui中使用completionHandler响应？

func fetchData(completionHandler: @escaping (Result<Data, Error>) -> Void) {
    // 执行异步操作，例如发送网络请求获取数据
    // 在操作完成时调用completionHandler
    // 如果成功，将结果以.success包装传递给completionHandler
    // 如果失败，将错误以.failure包装传递给completionHandler
}

struct ContentView: View {
    @State private var data: Data?

    var body: some View {
        VStack {
            if let data = data {
                Text("Data received: \(data)")
            } else {
                Text("Loading...")
            }
        }
        .onAppear {
            fetchData { result in
                switch result {
                case .success(let receivedData):
                    self.data = receivedData
                case .failure(let error):
                    print("Error: \(error)")
                }
            }
        }
    }
}