I followed (mostly) the instructions here: http://docs.opencv.org/doc/tutorials/introduction/ios_install/ios_install.html
I couldn't make a symbolic link to the Developer directory because I already had one (it contained MonoTouch), so I individually linked the files in /Applications/Xcode.app/Contents/Developer/ to my existing /Developer directory.
When I run "python opencv/platforms/ios/build_framework.py ios" I get a build error:
/Users/carlos/opencv/modules/highgui/src/cap_qtkit.mm:46:9: fatal error:
'QTKit/QTKit.h' file not found
#import <QTKit/QTKit.h>
^
1 error generated.
I searched for the QTKit.h file and found it in /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/System/Library/Frameworks/QTKit.framework/Versions/A/Headers/
It is therefore also in /Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/System/Library/Frameworks/QTKit.framework/Versions/A/Headers/
However, it seems like the build tool can't find this file.
The latest OpenCV commit ID in my repository is 580677f43d05d8d7cbc3cb72f01c0def334f67a2. I'm running OS X 10.8.4 and XCode 4.6.3.