使用Codable的Swift Rest API调用示例

本文介绍了使用Codable的Swift Rest API调用示例的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在跟踪有关使用Swift和Codable进行REST API调用的教程.尽管我在键入所有内容时都非常小心，但是我无法编译以下内容.谁能告诉我怎么了?另外，有人可以给我指出一个更好的教程吗?错误是:

I am following a tutorial on REST API calls with Swift and Codable. I cannot compile the following although I was careful when I typed all of it. Can anyone tell me what's wrong? Also, can anyone point me to a better tutorial? The error is:

捕获块无法访问

还有

在范围内找不到json

cannot find json in scope

import UIKit import Foundation struct Example: Codable { let userId: Int let id: Int let title: String let completed: Bool } class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view. } func getJson(completion: @escaping (Example)-> ()) { let urlString = "jsonplaceholder.typicode/todos/1" if let url = URL(string: urlString) { URLSession.shared.dataTask(with: url) {data, res, err in if let data = data { let decoder = JSONDecoder() do { let json: Example = try! decoder.decode(Example.self, from: data) completion(json) }catch let error { print(error.localizedDescription) } } }.resume() } } getJson() { (json) in print(json.id) } }

推荐答案

您可以使用"guard let"代替"do catch"

Instead of "do catch", you can use "guard let"

func getJson(completion: @escaping (Example)-> ()) { let urlString = "jsonplaceholder.typicode/todos/1" if let url = URL(string: urlString) { URLSession.shared.dataTask(with: url) {data, res, err in guard let data = data else {return print("error with data")} let decoder = JSONDecoder() guard let json: Example = try? decoder.decode(Example.self, from: data) else {return print("error with json")} completion(json) }.resume() } }

这不会不处理错误，所以我的解决方案只是解决您的问题，而不是针对所有类似情况的通用解决方案.

This does NOT handle errors, so my solution is just to an answer to your question, not a general solution for every similar cases.