SwiftUI Academy · 课时

使用 @Query 查询

在视图中获取并排序持久化数据。

使用 @Query 查询 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。

Fetching Saved Data

To show stored records in a view, you fetch them with @Query. It reads from your container and keeps the view fresh. 🔍

The @Query Property

Declare an array property with @Query and SwiftData fills it with every matching record. No manual loading needed.

@Query private var tasks: [Task]

Showing Results in a List

Pair @Query with a List to render rows from your data. Each saved object becomes one line on screen.

List(tasks) { task in
    Text(task.title)
}

Live Updates

A @Query view updates by itself when data changes. Insert a record and the list redraws with no extra work.

Sorting Results

Pass a sort key path to order your results. Here tasks come back alphabetically by title every time.

@Query(sort: \.title) var tasks: [Task]

Sort Direction

Add order to sort ascending or descending. Newest-first lists feel natural for things like recent notes.

@Query(sort: \.due, order: .reverse)
var tasks: [Task]

Filtering with Predicates

A #Predicate narrows results to records that match a rule. Only the rows you care about reach the view.

#Predicate<Task> { $0.isDone == false }

Applying a Filter

Pass your predicate to @Query to fetch a filtered set. This view shows only the tasks still left to do.

@Query(filter: #Predicate<Task> {
    !$0.isDone })
var open: [Task]

Multiple Sort Keys

Give an array of SortDescriptor values to sort by more than one field. Tie-breaks make long lists feel ordered.

@Query(sort: [SortDescriptor(\.priority)])
var tasks: [Task]

Counting and Empty States

Check the array's isEmpty to show a friendly placeholder. A clear empty state guides new users gently.

if tasks.isEmpty {
    Text("No tasks yet")
}

Queries Stay in Sync

Because @Query watches the store, your UI never drifts from the data. Save once and every query reflects it.

Quick Check

Quick check on querying data.

Recap: Querying

You used @Query to fetch, sort, and filter saved data, and watched the view stay live. Reading from SwiftData is now second nature. 🎯

常见问题解答

「使用 @Query 查询」课时是免费的吗？

是的 — 「使用 @Query 查询」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 @Query 查询」这节课中我会学到什么？

在视图中获取并排序持久化数据。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 3 节课，共 4 节。

「使用 @Query 查询」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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