The app looks nice, but there is a lot to improve, starting with the persistence layer.

There are several ways to save data in an iOS app. None of them are straightforward, so they are beyond the scope of this book. Yet, you can find two different ways to make data persist in the master branch (one method uses a file to persist the data, the other uses CoreData, a library to manage data in a database).

Another cool thing to implement is to add local notifications when the Todo task reaches the due date. Adding is also a quick way to increase the due date; you can add 10 minutes, 1 hour, or 1 day.