How to Force React Native app to be just RTL?

go to the file

MainApplication.java in this directory : android/app/src/main/java/com/YOUR_PROJECT_NAME

and add this code

I18nUtil sharedI18nUtilInstance = I18nUtil.getInstance();
sharedI18nUtilInstance.forceRTL(this,true);
sharedI18nUtilInstance.allowRTL(this, true);

to the onCreate method there, also dont forget to import this:

import com.facebook.react.modules.i18nmanager.I18nUtil;

That's because you didn't config the native side in android. Follow these steps:

1. Open this file:

   android > app > src > main > java > com > PACKAGE_NAME > MainApplication.java

2. Import I18nUtil package:

   import com.facebook.react.modules.i18nmanager.I18nUtil;

3. Find onCreate() function and paste this snippet at the end of function:

public void onCreate() {
  ...
  // Force the app not to change on device locale change
  I18nUtil sharedI18nUtilInstance = I18nUtil.getInstance();
  sharedI18nUtilInstance.allowRTL(getApplicationContext(), false);
}

Now when you change your device locale, the app layout wouldn't change!