How can I quickly filter by edited photos on iOS?

There is a feature for filtering photos in the iOS Photos app which allows you to quickly find previously edited photos. To access this capability click the three dots at the top right of the photos app (the three dots are located next to the "select" button).

After pressing the three dots (...) you will see the following screen:

Select "Filter" and the screen below will appear. On this screen select "edited"

Finally select "Done" and you will see only your edited photos.

You can reverse this by selecting the three dots again, selecting "Change Filter" and then setting the filter to "All Items"