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Private navigation palettes and LazyLayout

Status: Experimental opt-in navigation palettes; LazyLayout remains research only. Reviewed: 2026-09-23.

Selector spike

The community sample uses _UINavigationBarPalette, initWithContentView:, and UINavigationItem._setBottomPalette:. Reverse-engineered runtime headers also list _setTopPalette:. These names are not Apple API contracts. The bridge checks for the class and selectors at runtime before calling them.

The private path is gated to iOS 26.5, the only simulator runtime available for this spike. Both palettes appeared in an iPhone 17 simulator screenshot; the public fallback was also viewed with the flag off. No behavior or support range is claimed for other iOS versions or physical devices. LazyLayout has no verified selector or protocol signature, so no runtime implementation is included.

Public fallback and opt-in

<NavigationStack> accepts nested <TopPalette> and <BottomPalette> views. By default, public UINavigationItem.titleView hosts the top content and a public UIToolbar hosts the bottom content. Set enablePrivateNavigationPalettes="true" to try the private palette. A missing class, selector, or supported runtime automatically uses the public placement. All private runtime calls live in src/uikit/private_navigation_palettes.m.

<NavigationStack title="Discover" enablePrivateNavigationPalettes="true">
  <VStack><Label text="Discover" /></VStack>
  <BottomPalette><HStack><Label text="For You" /></HStack></BottomPalette>
</NavigationStack>

The opt-in example is demo/private-palettes/; it is excluded from the default example list. Public UINavigationItem and UINavigationController APIs remain the supported production path. For large collections use native List, not private LazyLayout.

Risk

Private APIs are unsupported and can change or disappear in any OS release. Using them can cause App Review rejection or removal after an update. The presence check does not guarantee layout, accessibility, or future behavior. Do not enable this option in an App Store app unless you accept that risk.