how to fix button at bottom in react native code example

Example 1: react native component at bottom center

bottomCenter: {
    flex: 1,
    justifyContent: 'flex-end',
    marginBottom: 30
}

Example 2: how to put react compnent to bottom

button: {  position: 'absolute',  bottom:0}

Example 3: react native button top right

<View>
    <Image
        source={require('../images/AppIntro/1.png')} 
        style={{ width: '100%', height: 150 }}
    />
    <Icon name="md-close" 
          style={{
                position: 'absolute',
                right: 5,
                top: 5,
          }} />
</View>