iOS Unity OpenGL Conflict

Hi, I am facing a problem that a conflict occurred in my iOS app. I have plugged an Unity iOS project to my existing iOS project. My existing iOS project is using an OpenGL based library which is called "GPUImage" (https://github.com/BradLarson/GPUImage). Everything works fine until I switch the controller between UnityController & GPUImage Controller. The error log is attached. Thanks!!