SwiftUI Academy · 课时

构建流式布局

创建能够换行的标签式布局。

构建流式布局 是 CoddyKit 上的免费 SwiftUI Academy 课时。这是第 4 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 Is a Flow?

A flow layout places items left to right and wraps to a new line when they run out of room, like word-wrapped text. 🏷️

Perfect for Tags

This wrapping behavior is exactly what you want for tag chips, hashtags, or filter pills of varying widths.

Start with Layout

Build it by conforming to the Layout protocol so you control wrapping yourself, since no stack wraps automatically.

struct FlowLayout: Layout {
    var spacing: CGFloat = 8
}

Measure Each Chip

In sizeThatFits, ask every subview for its size, then simulate placing them to find the total height needed.

let sizes = subviews.map {
    $0.sizeThatFits(.unspecified)
}

Track a Cursor

Keep an x and a y cursor. Move x rightward for each chip and reset when the next chip would overflow.

var x: CGFloat = 0
var y: CGFloat = 0

Detect Overflow

Before placing a chip, check if x plus its width exceeds the available width; if so, wrap to the next row.

if x + size.width > maxWidth {
    x = 0
    y += rowHeight + spacing
}

Advance the Row

After placing a chip, move x forward by its width plus spacing and grow rowHeight to the tallest chip seen.

x += size.width + spacing
rowHeight = max(rowHeight, size.height)

Place in the Second Pass

In placeSubviews, repeat the same wrapping math but call place at each computed point.

view.place(at: CGPoint(x: bounds.minX + x,
                       y: bounds.minY + y),
           proposal: .unspecified)

Return the Height

Your sizeThatFits should return the proposed width and the final y plus the last row height.

CGSize(width: maxWidth,
       height: y + rowHeight)

Drop It In

Now use it like any container: wrap your chips and the FlowLayout wraps them across as many lines as needed.

FlowLayout {
    ForEach(tags, id: \.self) { tag in
        TagChip(tag)
    }
}

Reusable Anywhere

Because it is a real Layout, your flow works with any views, adapts to width, and animates with the rest of SwiftUI. ✨

Quick Check

Recall what triggers a new row in a flow layout.

Recap

You built a wrapping FlowLayout with the Layout protocol, tracking a cursor to flow chips across rows automatically. 🎉

常见问题解答

「构建流式布局」课时是免费的吗？

是的 — 「构建流式布局」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。

「构建流式布局」这节课中我会学到什么？

创建能够换行的标签式布局。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 4 节课，共 4 节。

「构建流式布局」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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