React-native v0.12.0
now comes with support for Android out-of-the-box.
A common issue when writing cross platform (a.k.a isomorphic) code is determining which platform your code is being executed on.
Luckily there's a simple way:
import { Platform } from 'react-native';
if ( Platform.OS === 'ios' ) {
// iOS specific code here
} else {
// Android specific code here
}