Loading and progress indicators follow platform conventions

When async operations — API calls, uploads, data fetches — complete with no visual feedback, users perceive the app as frozen and repeat taps or abandon the action entirely. ISO 25010:2011 performance-efficiency attributes explicitly cover responsiveness perception, and loading indicators are the primary signal that work is in progress. Missing indicators also mask real failures: users cannot distinguish a slow network from a crashed operation, so they have no signal to wait, retry, or report a bug. Custom animations that diverge from platform conventions (native ActivityIndicator on iOS, material progress patterns on Android) erode platform coherence and increase cognitive load without adding value.

Use React Native's native ActivityIndicator for indeterminate progress and ProgressBar for determinate progress. Gate rendering on the loading boolean from your async state; do not conditionally mount an indicator that is never visible due to broken logic.

import { ActivityIndicator, View } from 'react-native';

export function DataScreen() {
  const { data, isLoading, error } = useFetch('/api/items');

  if (isLoading) {
    return (
      <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>
        <ActivityIndicator size="large" />
      </View>
    );
  }

  return <ItemList data={data} />;
}

For uploads or multi-step operations, prefer ProgressBar with a real progress value derived from bytes transferred or steps completed — avoid spinning indefinitely when determinate progress is available.