What is the code should be written to make my smart phone's camera as a webcam for Matlab ?

I download the "DroidCam" app for my smart phone and also download the "OS Generic Video interface" from support packages for Matlab ... What is the code should I write to make my smart phone's camera as a webcam for Matlab ? What I know if I want to Create the webcam object I write cam = webcam(); .. what should I write instead to make my webcam is my smart phone's camera ??