If you want to use any of the bundled icons, you need to add the icon fonts to your Xcode project. Just follow these steps:
Browse to node_modules/react-native-vector-icons and drag the folder Fonts (or just the ones you want) to your project in Xcode. Make sure your app is checked under “Add to targets” and that “Create groups” is checked if you add the whole folder.
Edit Info.plist and add a property called Fonts provided by application (or UIAppFonts if Xcode won’t autocomplete/not using Xcode) and type in the files you just added. It will look something like this:
Note: you need to recompile your project after adding new fonts, also ensure that they also appear under Copy Bundle Resources in Build Phases.
If you want to use the TabBar/NavigatorIOS integration or use getImageSource, then you need to add RNVectorIcons.xcodeproj to Libraries and add libRNVectorIcons.a to Link Binary With Libraries under Build Phases. More info and screenshots about how to do this is available in the React Native documentation.
Option: With CocoaPods
Add the following to your Podfile and run pod update:
pod 'RNVectorIcons', :path => 'node_modules/react-native-vector-icons'
Edit Info.plist as described above.
Option: With rnpm
$ react-native link
Note: Some users are having trouble using this method, try one of the others if you are too.
To configure for Android, see more: https://support.reactaz.com/knowledge-base/creating-and-using-a-custom-icon-font-for-android/