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使用 URLSession 调用 API

使用 async/await 获取数据。

使用 URLSession 调用 API 是 CoddyKit 上的免费 SwiftUI Academy 课时。这是第 2 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 SwiftUI Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 SwiftUI Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

What URLSession Does

URLSession is Apple framework for talking to the network. You give it a URL and it fetches the response for you. 🌐

Building a URL

Start with a valid URL. The initializer is optional because text can be malformed, so unwrap it before using.

let url = URL(string: "https://api.example.com/users")!

The async Fetch Call

The modern way to fetch is async/await. You await data from a URL and your code reads top to bottom, like normal.

let (data, response) = try await
    URLSession.shared.data(from: url)

You Get Data and Response

The call returns two things: the raw data bytes and a response describing status. You usually decode the data next.

Combining Fetch and Decode

Fetch then decode in two short steps. await the bytes, then hand them to JSONDecoder to get a typed value.

let (data, _) = try await URLSession.shared.data(from: url)
let users = try JSONDecoder().decode([User].self, from: data)

Async Functions

Wrap network work in an async function. Marking it async lets you use await inside and keeps the UI responsive.

func loadUsers() async throws -> [User] { }

Why throws Matters

Networking can fail, so fetch functions are throws. Callers must try, which forces you to think about errors.

Checking the Status Code

Cast the response and read its statusCode. A value of 200 means success, while 404 or 500 signal problems.

let http = response as? HTTPURLResponse
if http?.statusCode == 200 { }

Reusing the Shared Session

For most apps, URLSession.shared is all you need. It is a ready-made session with sensible default settings.

Custom Requests

For headers or POST bodies, build a URLRequest. Set the method and fields, then pass the request to the session.

var request = URLRequest(url: url)
request.httpMethod = "GET"

Keep Networking Off the UI

Always do fetching in an async context, never on the main thread directly, so taps and scrolling stay smooth.

Quick Check

Quick check on fetching data from a URL.

Recap: URLSession

You can now await data from a URL with URLSession, check the status code, and decode the bytes inside an async throwing function. 🚀

常见问题解答

「使用 URLSession 调用 API」课时是免费的吗？

是的 — 「使用 URLSession 调用 API」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 SwiftUI Academy 课程的其余内容，请升级到 CoddyKit PRO。 SwiftUI Academy 课程共包含 4 节课。

「使用 URLSession 调用 API」这节课中我会学到什么？

使用 async/await 获取数据。你通过在浏览器中直接运行的动手代码来练习 SwiftUI Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 SwiftUI Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 SwiftUI Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 2 节课，共 4 节。

「使用 URLSession 调用 API」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 SwiftUI Academy 课中编写并运行代码吗？

能。每节 SwiftUI Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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