Oleksii Bulenok
45 lines
2.2 KiB
Markdown
45 lines
2.2 KiB
Markdown
# @bsky.app\_\_expo-scroll-edge-effect.patch
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Fixes the iOS 26 scroll edge effect (the blur under the status bar) failing to
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attach on the New Architecture (Fabric).
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## Why
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The native view resolves the target scroll view by React tag:
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`scrollViewTag` (published from JS when the scroll view mounts) ->
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`appContext.findView(withTag:)` -> attach a `UIScrollEdgeElementContainerInteraction`.
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On Paper this resolved on the first try, because view-by-tag registration was
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serialized through the single UIManager batch pipeline - by the time the tag
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prop reached native, the scroll view was already in the registry.
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On Fabric there is no synchronous tag->view registry. The scroll view's
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`ComponentView` is registered when its mount transaction is applied, which is
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deferred relative to the JS commit that set the tag. So the one-shot
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`resolveScrollView` runs before the view is mounted and returns nil, the
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interaction never attaches, and the blur is lost. (The un-gated case happened to
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work only because the header's `didMoveToWindow` provided a late second attempt;
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a list mounted later - e.g. behind an `isActive` gate - had no such retry.)
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## What it does
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Makes resolution event-driven and self-healing instead of one-shot:
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- When `resolveScrollView` returns nil, it bumps a bounded counter and calls
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`setNeedsLayout()`; `layoutSubviews()` re-attempts as sibling views mount, so
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it retries exactly when the scroll view actually appears - no fixed timer.
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- `isAttached` stops re-running once resolved (no teardown/re-attach churn).
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- `resolveAttempts` / `maxResolveAttempts` bound the retries so a
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permanently-absent scroll view (list not rendered) cannot spin layout forever.
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- The budget is reset on every "fresh" trigger (prop change, entering the
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window) via `scheduleResolve()`, so each new tag gets a full retry budget.
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## Notes
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- iOS only; gated behind `#available(iOS 26, *)`.
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- This mirrors how `react-native-screens` handles the same effect on Fabric
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(resolve from the live view hierarchy and re-apply on mount/layout lifecycle
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rather than a single tag lookup). A cleaner long-term fix would move
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resolution to the scroll-view side, but this is the minimal change to the
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existing tag-based design.
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