Crysfel Villa from Modus Create has started a series of tutorials about React Native's layout system. Whenever you're uncertain about Flexbox, check this great tutorial that will walk you through building a NavBar like component.

React Native Layout System on Modus Create

The layout system is a fundamental concept that needs to be mastered in order to create great layouts and UIs. React Native uses Flexbox to create the layouts, which is great when we need to accommodate our components and views in different screen sizes or even different devices.