What I've Learned
I learned to use AutoLayout programmatically and build apps with UIKit. This app is basically made up of several standalone apps,
so I learned to build a layout that accommodates all of these standalone apps and can be easily updated/extended in the future.
I also learned to build the app with the best user experience in mind, meaning I only enable certain functionalities based on the data filled in.
For example, do not allow the user to calculate in the calculators until all data is entered, show corresponding error messages
and additionally use animations when values change.
Since this was the first app I made, it was also the first app I uploaded to the App Store. So I learned how to archive and upload
the app for review and also show it in the App Store afterwards.