Bring up an external Camera on Android device and use its display to view the live feed from the camera.
Support OTG Function:allow full compatibility with ALL OTG Compatible Android devices - smartphones and tablets.Install USB Camera or USB Web Camera or CameraFi or CameraFi Live  (free apps on Google Play),plug the camera and you are ready to go.
Smartphone are able to be supported OTG to recognize USB camera.

It works only for over Android Version 4.3 and doesnt work on Apple IOS