# 補充資料

## [ Building Layouts with Stack Views](https://developer.apple.com/documentation/swiftui/building-layouts-with-stack-views)

* If your layout has one dominant view that defines the size of the layout, use the `overlay(_:alignment:)` or `background(_:alignment:)` view modifier on that view.
* If you want the final view size to come from an aggregation of all the contained views, use a `ZStack`.


## [ Making Fine Adjustments to a View’s Position](https://developer.apple.com/documentation/swiftui/making-fine-adjustments-to-a-view-s-position)

the `offset(x:y:)` modifier uses the parameters of x and y to represent a relative location within the view’s coordinate space.

> ZStack 沒有指定 alignment，所以 Image 會在正中間(80,80)。 `.offset(x: 40.0, y: -40.0)` 加上這個偏移的話，就會坐落在第一象限。


## [Creating custom paths with SwiftUI](https://www.hackingwithswift.com/books/ios-swiftui/creating-custom-paths-with-swiftui)

|尖頭三角形|圓頭三角形|
|---|---|
|`.stroke(.blue, lineWidth: 10)`|`.stroke(.blue, style: StrokeStyle(lineWidth: 10, lineCap: .round, lineJoin: .round))`|
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## [ Laying Out a Simple View](https://developer.apple.com/documentation/swiftui/laying-out-a-simple-view)

1. The `ZStack` proposes a size to its child views, the `Circle` and `Text` views.
1. The `Circle` expands up to the size offered, while the `Text` takes just enough space for the string it contains.
1. The `ZStack` returns the size of its largest child view, in this case the `Circle`.

| MessageRow的大小被HStack 決定 | 變成加了約束寬度的ZStack主宰者 |
|---|---|
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## [How to control layout priority using layoutPriority()](https://www.hackingwithswift.com/quick-start/swiftui/how-to-control-layout-priority-using-layoutpriority)

All views have a layout priority of 0 by default. Raising a view’s layout priority encourages the higher priority view to shrink later.