Im having problems setting it up in codeblocks, it doesnt detect cv::, I've linked and set the build options but dunno if thats correct.
Post a full rebuild log, see instructions here (https://wiki.codeblocks.org/index.php/FAQ-Compiling_(general)#Q:_How_do_I_report_a_compilation_problem_on_the_forums.3F).
What do you mean by "doesn't detect"?
Depending on the os, on linux it is often enough to add e.g. `pkg-config opencv4 --cflags` under Project options | other compiler options and `pkg-config opencv4 --libs` under other linker options. Then the compiler can find the includes and the linker the libraries.
Code completion might be a different story. I do not care a lot about it.