If you really want to build mobile apps, there are two MAIN routes:

1. Native

2. Hybrid/crossplatform

Native

Native apps are original apps build with original technologies that have been specially created for the particular mobile OS.

If you want to build android native apps, consider using Java or Kotlin . Both languages are similar and run on the same engine. Kotlin is gaining more popularity as it is now possible to even build native iOS apps with it.

To build IOS native apps , you will need to work with either Objective-C or Swift. Both are also very similar and if you have experience with c++ it will be easy to pick up.

Hybrid

Hybrid apps are apps that combine elements of native apps with web apps to create an experience that is as close to native as possible. To build hybrid apps, their lots of technologies out there. But the most recommended are: Flutter and React Native

Flutter is a framework or a system of tools that help you build nice android and IOS apps with language called - dart . Flutter is a great framework because just like most hybrid app development methods, you can write the code for the app once and build it for different operating systems like android, iOS, Mac, Windows, Linux.

So, instead of writing separate codes for the android and iOS versions of a mobile app. Which will take a lot of time and expertise. I can write the app in one language and optimise it to work differently on different platforms.

React Native is just like flutter but it works on Javascript. So you must know a lot of Javascript to build apps with react Native.

You might ask, which is better? Native? Hybrid? Flutter? React?

Well... it depends.

Native apps perform better than hybrid apps, they are more efficient and their app sizes are smaller. Although, everyday, a lot of efforts are being made to optimise hybrid apps and make them match native apps in terms of performance. But I will advise that if you plan to build a heavy duty app (like a gaming app, or some graphics/video editor, browsers), Go native.

But if you're building more general purpose utility apps like social networks, navigation apps, you can work with hybrid solutions. Your favorite apps like facebook and instagram were built with React Native.

Google has a lot of active apps, built with flutter.

As for which is better , between flutter and react native. Anyone is cool. Just pick anyone you're okay with.

Os app? native app? lience permission must repuest and allowed?