Back button/navigation uses platform conventions

iOS users swipe from the left edge to go back without looking — it is the most frequent navigation gesture in the OS. Replacing it with a custom back button forces users to reach up to the top-left corner one-handed, which is physically uncomfortable on phones above 6 inches and drives session abandonment. On Android, a broken hardware back button is an Android Vitals crash-class signal and directly lowers Play Store visibility.

Use React Navigation's native stack — it wires up iOS swipe-back and Android hardware back for free. Do not disable gestureEnabled without a documented reason:

import { createNativeStackNavigator } from '@react-navigation/native-stack';
const Stack = createNativeStackNavigator();
<Stack.Navigator screenOptions={{ gestureEnabled: true }}>
  <Stack.Screen name="Home" component={HomeScreen} />
  <Stack.Screen name="Detail" component={DetailScreen} />
</Stack.Navigator>

If you use a custom navigator, add a BackHandler listener on Android.

• ID: mobile-ux-patterns.platform-conventions.back-button-convention

• Severity: high

• What to look for: Check the navigation library setup (cite the actual library and version). On iOS, verify swipe-back gesture is enabled (gestureEnabled: true or React Navigation default). On Android, verify hardware back button handling. Enumerate all screens and check back navigation consistency.

• Pass criteria: iOS uses swipe-back gesture (React Navigation default) or visible back button in top-left on at least 100% of navigable screens. Android hardware/on-screen back button works correctly. Back navigation is consistent across all screens.

• Fail criteria: iOS has no swipe-back and relies on custom back buttons on any screen, or Android back button does not work on any screen. Back navigation is broken or inconsistent across screens.

• Skip (N/A) when: The app is single-screen with no navigation stack (no route pushing or screen transitions).

• Detail on fail: Quote the navigation configuration. "iOS app has custom back buttons instead of swipe-back gesture — users must tap a button instead of using familiar gesture." or "Android back button pops screen correctly but does not close the app from root navigation."

• Cross-reference: For navigation accessibility (screen reader announcements on route changes), the Accessibility Fundamentals audit covers focus management during navigation.

• Remediation: Use React Navigation, which handles platform conventions automatically:

  import { NavigationContainer } from '@react-navigation/native';
  import { createNativeStackNavigator } from '@react-navigation/native-stack';
  
  // iOS: automatic swipe-back gesture
  // Android: hardware back button support
  const Stack = createNativeStackNavigator();
  
  export default function Navigation() {
    return (
      <NavigationContainer>
        <Stack.Navigator>
          <Stack.Screen name="Home" component={HomeScreen} />
          <Stack.Screen name="Detail" component={DetailScreen} />
        </Stack.Navigator>
      </NavigationContainer>
    );
  }
  

  For custom back button on iOS (if needed):

  <Stack.Screen
    name="Detail"
    component={DetailScreen}
    options={{
      headerBackTitle: 'Back',
      headerBackTitleVisible: true,
    }}
  />