opencv IOS - MacTypes.h, ambiguous references

edit

You need to specify the reference.

cv::Ptr

I know this is an old question, but it was at the top of the searches when I encountered the same issue, so I thought I would attempt to clarify the problem and solution for others that may hit this in a search result:

The problem encountered is a conflict between similar type names declared in OpenCV and iOS, for example - Ptr, Size, Rect, etc.

In order to rectify these conflicts, make sure that the OpenCV imports are declared before any iOS imports, and make sure that there is not a using namespace cv declared before the iOS imports. If this error occurs, the most likely culprit is that the statement "using namespace cv" is declared before the iOS imports, which causes the ambiguous reference in the compiler.

you have to use namespace like this;

for example You will use Point;

define in cv namespace

namespace cv{
    Point maxLoc;
}

And use it like this;

minMaxLoc(histForRed, 0, 0, 0, &maxLoc);

NSLog(@"R x: %d", maxLoc.x);
NSLog(@"R y: %d", maxLoc.y);