Tune with Capo
When you use a capo, the notes on your guitar change. This can get fiddly when tuning, especially if you're using alternate tunings that you're not as familiar with. With the app, you don't have to think about transposed strings.
Tip: When tuning with the capo, it is particularly important that you first tune the string a little lower and then tune "from below" towards the tone. Because the capo clamps the strings, you have to pull the string gently after you have tuned it a little lower and then tune it.