Right Bar Button vs Bottom Button – iOS

I can't decide the placement of the button that will take the user to the next screen or that will submit a form.

Apple uses both right bar button and bottom button in different cases. It's obvious that reaching the bottom button is more comfortable than reaching the right bar button. Yet, the bottom button takes too much space and makes it harder to view the content that is in the middle of the screen (especially when the keyboard is active).

Which one would you recommend? Or, you have a different approach?