A couple of potentially useful gadgets:

FLIROne

FLIR capability for you phone. Many potential uses, but I am not sure of the price. I have heard around $399.

IN1Case

iphone case with tools inside. I think this one would be much better with a battery pack and attachable stand alone GPS that does not rely on cell phone signal. It could then be considered survival gear.

Just to throw these out there in case you haven't seen them. No experience with either one, yet. I have reserved a FLIROne, but they did not list a price.

Standard disclaimer, no affiliation with either company.