Want Shutter Release for iPhone

I've been looking for a one button shutter release for iPhone 4 with no luck. I shoot on a handle and having a shutter release near my thumb is the goal.

I know I can use my earbuds inline volume control but dangling earbuds is too clumsy a solution. Any suggestions out there? B&H had several designed for DSLR but I'm not sure if they'd work on an iPhone. Might actually damage it.

FYI: you CAN trigger the iPhone camera Apple supplied with the volume control buttons on the phone or inline earbuds. This also works for the recently updated 645 Pro ap and a few other camera aps but not all.