I’m not an iphone user so don’t quote me, but I know dangerous things makes an android app (possibly an iphone app) to lock and unlock a phone. It depends on the tag you get, you could use it for work if they use a proximity card system, you could use it to unlock/lock your car, your door lock, computer, etc. The car and computer will need a few mods to make happen, but people have done it already. The door lock is easier, they sell locks that are compatible with certain tags.
You can find that information (definately not complete) here: Product Compatibility List