SwiftUI TabView(.sidebarAdaptable) does not reliably animate content resize when switching between sidebar and top tab bar on iPad

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Ray-Liuhechuan OP

Created 2d

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Hi everyone,

I’m building an iPad app in SwiftUI using the adaptive tab navigation pattern:

    Tab(value: .overview) {
        OverviewView()
    } label: {
        Label("Overview", systemImage: "archivebox")
    }

    Tab(value: .gallery) {
        GalleryView()
    } label: {
        Label("Gallery", systemImage: "shippingbox")
    }

    Tab(value: .canvas) {
        CanvasView()
    } label: {
        Label("Canvas", systemImage: "rectangle")
    }

    Tab(value: .record) {
        recordView
    } label: {
        Label("Record", systemImage: "plus")
    }
}
.tabViewStyle(.sidebarAdaptable)
.tabViewCustomization($tabCustomization)

The issue is that when the adaptive tab bar switches between the sidebar placement and the top bar placement on iPad, the content area resize animation is unreliable.

The system navigation chrome changes correctly, but some tab contents jump directly to their final width instead of smoothly animating with the sidebar/top bar transition. Interestingly, one of my record views appears to animate consistently, so it seems the system transition itself is possible, but some view hierarchy or navigation structure may be preventing the animation in other tabs.

Each major tab currently owns its own NavigationStack. For example, OverviewView, GalleryView, and CanvasView each have a NavigationStack as their root view. The Record tab conditionally shows different recording views, and one of those views also contains its own NavigationStack.

I have already tried several approaches, but none solved the issue reliably:

Observing @Environment(.tabBarPlacement) and adding .animation(..., value:)
Reporting tabBarPlacement upward using a PreferenceKey and wrapping the update in withAnimation
Wrapping tab contents in GeometryReader or other outer layout containers
Temporarily removing .tabViewCustomization($tabCustomization) and .customizationID(...)
Reducing the implementation to the simplest documented TabView(selection:) + Tab(...) + .tabViewStyle(.sidebarAdaptable) structure

Some of these attempts actually made the animation behavior worse, so I reverted them.

My questions are:

1.Is the content area expected to animate automatically when TabView(.sidebarAdaptable) changes between sidebar and top bar placement on iPad? 2.Is it recommended for each tab to own its own NavigationStack in this setup? 3.Could tabViewCustomization(:) or customizationID(:) affect the sidebar/top bar transition animation? 4.Is there an official SwiftUI pattern for preserving the system animation transaction during this adaptive tab bar placement change? 5.If this is expected behavior or a current limitation, what structure would Apple recommend for this kind of iPad navigation?

Thanks in advance!

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