return (
<ImageBackground source={...} style={{width: '100%', height: '100%'}}>
<Text>Inside</Text>
</ImageBackground>
);
<ImageBackground source={require('background image path')} style={{width: '100%', height: '100%'}}>
<View style={{position: 'absolute', top: 0, left: 0, right: 0, bottom: 0, justifyContent: 'center', alignItems: 'center'}}>
<Text>Centered text</Text>
</View>
</ImageBackground>