Virtual Reality for iPhones

There seems to be very few guides to make virtual reality games on iPhones
I was wondering if any can help, and give af few examples.
Any help is appreciated!

Is there even a VR headset for iPhone? I haven’t heard of any

I am just getting started with UE4 (literally - first day) but I did implement vr for an iphone app… The app isn’t done (I want to port it to UE4 before continuing), but making the app work with a vr headset (Google Cardboard -type) was relatively easy using opengl with GLKit. I just track two eye positions, slightly offset, and then render twice, using two side-by-side viewports, each taking up half the screen. Each render used an appropriate view matrix for the respective eye positions. The other required component is head-tracking which Apple’s MotionKit does really nicely. I don’t know how easy this would be to implement in UE4. By the way, the VR One works nicely with iphone 6 for a head-mounted vr, but making a real game with it would probably require that the players have a bluetooth game controller as well.