GUI Buttons doesn't work on iOS for the attached project which consumes some native APIs for screen-rotation and screenshot.

Steps to Reproduce:
- Open attached project.
- Build and Run on an iOS device.

Note: GUI Buttons doesn't work.

Expected Result: - Should capture a screenshot by clicking the top-left button.
- Orientation should change clicking the top-right button.

Reproduced on : 2018.1.0b1,2018.1.0b3

Working fine on : 2017.3.0f3, 2018.1.0a3, 2018.1.0a7

Test Devices: iPhoneX (OS-11.2.2) , iPhone8Plus(OS-11.0.3),iPhone5S(OS-10.3.3), iPadPro(2017) 12:9 (OS-11.0.3)