I read the response about iPhone screens being too small for proper use. However, I’d still like to suggest a limited iPhone app would be helpful to mobile DJs and producers with simple lighting needs like in a local theater.
I do both and I often want a pocket solution while on the move in an environment like a small theater or simply having basic control options in an easy interface during a DJ set.
For theater, it can be helpful to have quick access to a few customizable controls for lights that can be accessed in lighting booth or backstage (or anywhere nearby). For mobile DJ gigs, I want to control a few lights only via easy access to changing less than 10 presets. With a small lighting rig of less than 6 lights, all I need is a small screen with a few presets for simple stuff like color changes, chasing routines, strobing, sound activation, etc.
A phone screen fulfills both needs by being both small enough to carry around and wedge between gear in a DJ booth for quick and basic light preset changes.
Of course, all of this relies on a hardware solution that supports wireless/WiFi iPhone access to a DMX controller which is a whole other discussion, especially when trying to avoid using a laptop in favor of just iOS device control for small lighting needs.