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@Observable 宏

让类具备可观察性，使视图能够跟踪它。

@Observable 宏 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。

The Problem to Solve

A plain model class holds data, but SwiftUI will not redraw when that data changes. We need to make the class observable.

Meet @Observable

The @Observable macro marks a class so SwiftUI watches its properties and refreshes any view that reads them. ✨

@Observable
class Counter {
    var count = 0
}

What a Macro Does

A macro generates extra code for you at compile time, so one short attribute adds all the change-tracking plumbing.

Importing Observation

The macro lives in the Observation framework, so add an import at the top of the file before you use it.

import Observation

@Observable
class Counter { var count = 0 }

No Wrappers Needed

With @Observable you mark plain stored properties. No per-property wrapper is required for SwiftUI to track them.

@Observable
class Counter {
    var count = 0
    var name = "Taps"
}

Reading Triggers Tracking

SwiftUI only refreshes for the properties a view actually reads in its body, so unused values cost you nothing.

Writing Triggers Updates

When you change a tracked property, every view that reads it is automatically scheduled to redraw.

model.count += 1  // views reading count refresh

Computed Properties Work Too

A computed property built from tracked values also updates views, since reading it reads its inputs.

@Observable
class Counter {
    var count = 0
    var label: String { "Taps: \(count)" }
}

Granular by Default

Tracking is granular: changing one property only refreshes views that read that property, not the whole screen.

Replacing ObservableObject

@Observable is the modern replacement for the older ObservableObject plus @Published pattern, with far less boilerplate.

Ignoring a Property

Mark a value with @ObservationIgnored when it should not trigger updates, like a cache or internal scratch value.

@Observable
class Counter {
    @ObservationIgnored var cache = 0
}

Quick Check

Time to check your grip on @Observable.

Recap

You made a model @Observable, so SwiftUI tracks the properties your views read and redraws them precisely when those values change. 🎉

常见问题解答

「@Observable 宏」课时是免费的吗？

是的 — 「@Observable 宏」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。

「@Observable 宏」这节课中我会学到什么？

让类具备可观察性，使视图能够跟踪它。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。

「@Observable 宏」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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