In theory just just write code once and have the app ran on both platforms. In practice it's much more complicated, and whenever you need to do more than the fr

In theory just just write code once and have the app ran on both platforms. In practice it's much more complicated, and whenever you need to do more than the framework offers your situation is much more complicated than in the case of native development. Also some features are implemented in different ways on both platforms and you need to get into details anyway. So being familiar with native APIs is a great advantage even if you use the cross-platform approach.