xcodeswiftuizstackview-hierarchy

SwiftUI ZStack and Xcode 3D View Hierarchy

I'm learning SwiftUI. When I have a ZStack say

ZStack {
   Image(systemName: "globe")
        .imageScale(.large)
        .foregroundColor(.accentColor)
   Text("Hello, world!")
}

I am expecting that the Text is overlayed on top of the Image. Why is is though that when I look at it in Xcode's Debug > View Debugging > Capture View Hierarchy, enter image description here

I get a 3-D view where the Text is not the "top most". Instead I see the Image. Is my understanding mixed up? Appreciate the clarification. Thanks.

Solution

  • When you view the ZStack in Xcode's Debug > View Debugging > Capture View Hierarchy, the view hierarchy is represented in a 3-D space to help you visualize the layout of the views.

    In this 3-D representation, each view is positioned in a 3-D space with an x, y, and z coordinate. The camera is positioned at a specific location in this 3-D space, and the views are rendered based on their position relative to the camera.

    In the case of the ZStack with an Image and a Text, the Image and Text are positioned at different depths in the 3-D space. The Image may be positioned closer to the camera than the Text, which makes it appear as though it is in front of the Text.

    However, this is just a visual representation and does not affect the actual layout or behavior of the views. In reality, the Text is still positioned on top of the Image in the ZStack, and will respond to touch events before the Image.

    The reason I say this is just a visual representation and does not affect the actual layout or behavior of the views, you can refer to the following example, the UI is different but the green frame is still the same:

    enter image description here

    and

    enter image description here

    I hope this explanation helps!