Recent experiments with Pythonista ui building has proven to me the value of designing user interfaces with the pyui Editor. Creating UI elements in Python code that supports multiple screen sizes is far more verbose and error prone than I originally thought.
The trouble with .pyui files is that that are difficult to copy and paste when posting to and downloading from this forum and GitHub, etc. This has been eased somewhat in the new beta that allows you to change the file extension from .pyui to .json and back. This forum contains several other very interesting approaches to this problem.
I like pyui_embed.py because it creates a separate standalone .py file that allow you to mess around with the attributes of ui elements and see exactly how Pythonista will render them. It also puts a few lines of code onto the clipboard which you can paste into your main .py file so that the two .py files will work together to load the view without requiring the .pyui file.
If you are not running Pythonista v1.6 you will need to comment out the dialogs module calls and hard code filename to point to a .pyui file in the current working directory.