Controlling variables from your phone

Hey folks,
I know it's possible but I just don't know how to do it. I would like to make certain variables have an option to be filled in. I am trying to make an Arduino controlled motorized slider and that requires me to decide how long or how fast I want the slider to move. Is it possible to edit variables and make fill in the blank options on my iPhone? Is it possible to do this while photographing or in the field? Would I need wifi?

Thank you for any responses

Does your phone have Bluetooth?

Can you change a variable? I'd say they'd be poorly named if you couldn't.

Whatever your method of input, it will set some variable accordingly. Your job is just to give the program things to do in all scenarios.