Multi-device support — iPad not displaying a stretched iPhone layout, tablet optimization

Apple guideline 4.2 requires that universal apps look great on all supported device sizes — a stretched iPhone layout on iPad is a named rejection reason, not a judgment call. The ISO 25010 portability.adaptability metric applies directly here: an app that renders a 375px-wide phone layout on a 1024px iPad screen fails adaptability by definition. This is especially common in AI-generated React Native code that uses Dimensions.get('window').width as a static constant at module load time rather than as a reactive value — the measurement is correct on first launch but does not respond to device rotation, split-screen mode, or Stage Manager on iPad.

The fastest fix for a phone-first app is to explicitly exclude iPad support:

// app.json
{
  "expo": {
    "ios": { "supportsTablet": false }
  }
}

If iPad support is desired, replace all fixed width: 375 values with useWindowDimensions and implement breakpoint-based layouts:

import { useWindowDimensions } from 'react-native';

function Screen() {
  const { width } = useWindowDimensions();
  const isTablet = width >= 768;
  return isTablet ? <TabletLayout /> : <PhoneLayout />;
}

Remove any one-time Dimensions.get('window') call at module scope — these do not respond to orientation changes or split-screen. Test on iPad Simulator (any model) before submitting as a universal app.