Using Xcode for OpenCV projects

OpenCV is the most mature computer vision library in the world. Xcode is the best IDE on macOS. OpenCV is written in C++ and various bindings (first- and third-party) exist for most popular language. I prefer to work in C++. Although Xcode has excellent support for C++ projects, getting it to play nicely with OpenCV is rather tricky.

UIWindow

A window is an instance of the UIWindow class and it is the topmost element of any application UI's hierarchy. It doesn't draw any visual object and can be considered as a blank container for the UI elements called views. An application must have at least one window that normally fills the entire screen.