As curiosity is that Nick Lee of American design studio Tendigi built a case that allows an iPhone 6s Plus running Android Marshmallow, or rather show Android.
The case is made with 3D printers and includes a 64-bit Cortex-A53 processor and a 650mAh battery.
Lee took the Android source code from AOSP and managed to get the hardware to run the system.
A specially written iOS app communicates finally with the case, which is connected via the Lightning connector.
The shell runs Android and streams simply picture to your phone.
Those who want to know more about how Nick Lee conducted the experiment can be advantageously visit Tendigis website.