OpenCV on iOS - GPU usage?

I am trying to develop an iOS app that performs real time effects on video from the camera, much like Photobooth on the iPad. I am familiar with the API for OpenCV but am worried about the performance on iOS if most processing is completed on the CPU versus the GPU. Libraries like GPUImage would most likely do the trick but I would rather stay with something I am familiar with. So, does anyone know if OpenCV compiled for iOS uses the GPU?