Keep in mind, editing is easier to do in an editing program like Premiere Pro.
Editing is cutting shots together to tell a story. After Effects is used for compositing, visual effects, and motion graphics. You use AE to make shots. You then use those shots in an edit in Premiere to tell your story. You COULD edit in AE because you can trim clips in it, but it's a really painful way to work.
Cut in Premiere, do effects in AE.
In any case, you could use your iPhone to do it.
Speaking of your iPhone, have you seen Adobe's mobile apps? You can actually edit video on your phone!
How can I put an iPhone video onto my computer?