Apple Mach-O linker and multiple “undefined symbols” error using OpenCV

Building on Cthutu’s answer, to add libc++.dylib to your project:

1. Select your project (the blue file) in your project navigator
   (Command 1 if it’s hidden)
2. Select your target
3. Go to Build Phases
4. Expand “Link Binary With Libraries”
5. Click the “+”
6. Type libc++.dylib in the search bar.
7. Select the libc++.dylib file and press “Add”