Recommended Toolsets for Developing for IOS and Android

I have done small amounts of programming for IOS and for Android, but now I need to create something that works with both.

What are the recommended toolsets to accomplish that for a beginner?

The app will be a simple control device for robots over Wi-Fi.

Sadly, in most cases, the best approach is to write entirely separate apps for each platform.

Recommended Toolsets for Developing for IOS and Android
 
 
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