Are you sure you are running on Python 3?

https://docs.python.org/3/library/plistlib.html

Why not provide us with the code that you have written so far? That would help us to see what you are seeing without having to rewrite it.

str.replace(substr, ‘’) might be part of the solution.

https://github.com/brandon-rhodes/pyephem click on the colored bar that is just above "Branch: master, New pull request". You will see there that this repo is ~73% C code and ~4% Python code. Apple's iOS guidelines make it difficult for Pythonista to support such an app. If a repo is "pure Python" then you have a fighting change to make them work but when they are largely non-Python, odds are low.

What happens when you click the "Download on the App Store" button on http://omz-software.com/pythonista

What happens when you click on:

• https://itunes.apple.com/za/app/pythonista-3/id1085978097
• https://itunes.apple.com/us/app/pythonista-3/id1085978097

https://www.economist.com/science-and-technology/2018/07/21/python-has-brought-computer-programming-to-a-vast-new-audience

Apple locks down the iOS (amd Mac OSX!) so that this kinda stuff is near impossible in any language without jail-breaking the device.

https://forum.omz-software.com/search/wifi?in=titlesposts

Guido van Rossum has given up the title of "Benevolent Dictator For Life" for Python

https://www.zdnet.com/article/python-language-founder-steps-down/

Why do you want Python 3.7?

iOS does not work that way on ObjectiveC, Swift, or Python. On iOS, apps remain in RAM until a user physically pushes them out of RAM.