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The discussion about how to choose the best mobile app frameworks for iOS and Android mobile design and development has started a long time ago. At the moment, one of the most popular comparisons is Ionic vs React Native. Both of these frameworks are among the most famous and used cross-platform development environments. If you want to develop an app, that will be offered not only for mobile devices, but for myriad platforms - Ionic is probably your choice. In this case, you will significantly improve your web presence.
On the other hand, if your main goal is iOS and Android mobile design and development - React Native will suit you more. It provides a better user experience for these platforms.