C++ Implementation from C

edit

I found some code online that I am interested in using but I believe it was written in C and I need the C++ implementation for iOS development. Here is the line of code

patch=I(NSMakeRange(i,i+blockSide+1),NSMakeRange(j,j+blockSide+1));

Getting the error of:

No matching function for call to object of type 'cv::Mat'

Here is how I am defining patch

cv::Mat patch;

Anyone know how I can fix this? Thanks.