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使用 @State 管理自有对象

使用 @State 持有可观察模型。

使用 @State 管理自有对象 是 CoddyKit 上的免费 SwiftUI Academy 课时。这是第 3 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。

Who Owns the Model

An observable model needs an owner: a view that creates it and keeps it alive for as long as the screen exists.

@State Owns the Instance

Use @State to let a view own an observable model. The view creates it once and holds onto it across redraws.

@State private var model = Counter()

Why @State Here

Without @State, a fresh model would be made on every redraw, wiping your data. @State persists the same instance.

Reading the Model

Read tracked properties straight from the model in your body, and the view refreshes when they change.

Text("Count: \(model.count)")

Calling Model Methods

Trigger behaviour by calling the model methods from your controls, keeping the view free of the actual logic.

Button("Add") { model.increment() }

Mark It private

Keep owned state private so other types cannot reach in and mutate the model behind the view back.

@State private var model = Counter()

No $ to Read

To read an observable model you use it directly. The dollar sign $ is only for making a binding, which we cover later.

A Full Owned View

Here a view owns the model, reads its value, and updates it on tap, all in one tidy place.

struct CounterView: View {
    @State private var model = Counter()
    var body: some View {
        Button("\(model.count)") { model.increment() }
    }
}

Survives Redraws

Because @State is managed by SwiftUI, your model survives every body re-evaluation while the view is on screen.

One Owner Rule

A model should have a single owner. Child views receive access instead of each making their own copy.

Lifetime Tied to the View

The model lives as long as its owning view. When the view leaves the screen for good, the model is released.

Quick Check

Let us confirm how ownership works.

Recap

You used @State to let a view own its observable model, so a single instance survives redraws while the view reads and updates it. ✨

常见问题解答

「使用 @State 管理自有对象」课时是免费的吗？

是的 — 「使用 @State 管理自有对象」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 @State 管理自有对象」这节课中我会学到什么？

使用 @State 持有可观察模型。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 3 节课，共 4 节。

「使用 @State 管理自有对象」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。

此课程中的所有课时

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