Does anyone know how to make a "painting" shader?

Alright so I found this project online that does exactly what I need https://medium.com/@shahriyarshahrabi/mesh-texture-painting-in-unity-using-shaders-8eb7fc31221c
It changes the pixels colors in an area.
But it doesn't work on IOS. I am trying to solve this problem for over a week and I don't what to do I was thinking on creating it from scratch but I don't really know how to do it.

You can see the post about the problem I have here https://forum.unity.com/threads/shader-works-on-android-but-it-is-black-on-ios.835177/#post-5525773
And a previous problem https://forum.unity.com/threads/cus...g-the-platform-to-mobile.824139/#post-5501224

I was hoping that someone here knows how to do it or already has and can help me with anything and if you can't post the code I will after everything is done because I really can't find other painting script like this online.

Any help is appreciated and thank you

 

I can only point you to this asset which I've used in a different scenario (not iOS). You might want to contact the author to find out whether it works on iOS.

 

I am going to check it out. Thank you