expo-animation

Use Gesture.Pan with a shared value for translateY, capture the current value in onStart, and decide dismissal from projected velocity rather than distance alone. Hand the gesture velocity to withSpring so there is no seam when the finger releases, and derive the backdrop opacity from the same value.

Use Reanimated for anything a finger touches or anything derived from scroll. Core Animated cannot be driven by a gesture without crossing the bridge, and useNativeDriver only supports transform and opacity, while Reanimated worklets run on the UI thread even when JS is busy.

Stutter usually comes from setState in gesture or scroll handlers, animating layout properties like height or width, or scheduling back to the JS runtime every frame. Move values into shared values with useAnimatedStyle and verify on a release build, since Expo Go hides these problems.

Use a spring whenever a finger was involved, because springs carry velocity through an interruption while timing curves restart. Everything else uses timing with ease-out for entering or exiting elements and ease-in-out for on-screen movement, staying under 300ms for UI.

Yes, presentation: 'formSheet' gives a real native sheet on both platforms with detents via sheetAllowedDetents. Android caps detents at three, shows no grabber, and cannot host nested stacks inside the sheet, so keep sheet content to a single screen.

The most common cause is a missing GestureHandlerRootView wrapping the app root, which silently disables all gestures. Also confirm dependencies were installed with npx expo install so versions match the SDK, and that the worklets Babel plugin is configured.