I am trying to use OpenCV within Xcode. I was following this thread but OpenCV's dylib are in /usr/local/lib and not in /opt/local/lib is there a way to see the first path within Xcode? Should I change the install path of OpenCV? I don't know if there's a difference between /usr/local and /opt/local
That link assumes that /opt/local/ is the install path of the OpenCV libraries. You should be able to simply replace /opt/local/ in the tutorial with /usr/local/.
And yes, the two paths are different locations.