Modal and alert styling matches platform conventions

iOS users expect modals to slide up as a sheet with a dismissible drag handle — a centered Material dialog on iOS feels foreign and users miss the close button. On Android, a slide-up sheet where a centered dialog is expected looks like a bug. Using Alert.alert() for simple confirmations inherits the correct system styling for free; building custom-styled replacements almost always gets the platform convention wrong.

Set presentationStyle per platform on every Modal, and use the native Alert.alert() for any confirm/cancel dialog instead of a custom component:

import { Modal, Alert, Platform } from 'react-native';
<Modal visible={visible} presentationStyle={Platform.OS === 'ios' ? 'pageSheet' : 'overFullScreen'}>{/* content */}</Modal>
Alert.alert('Delete?', 'This cannot be undone.', [
  { text: 'Cancel', style: 'cancel' },
  { text: 'Delete', style: 'destructive' },
]);