There are many awesome smartphone apps available for those of you who want to learn a guitar. To keep up with your lessons on a smartphone easily, you are better off investing in a decent stand. These 2 smartphone holders for guitars could also prove useful:
Acoustic CAPO Q: it can be used as a capo and a smartphone holder. Works for any device ranged from 57mm to 80mm. Offers 360 degree rotation.
Castiv – Guitar Sidekick: works with any smartphone measuring 2.3″ to 3.3″. It can be used with acoustic, electric, or classical guitars. You can switch between portrait and landscape views easily.
These accessories hold your phone and help you practice guitar easier. They are not too expensive, which helps.