How to make a Mac OSX Cocoa application fullscreen?

I have been trying to make my Mac application enter fullscreen now for a while but can't get it to work. According to the Apple developer center, I should use enterFullScreenMode:withOptions: which gives me, method enterFullScreenMode not found.

Everywhere I google there seems to be people having issues with making their app fullscreen, so what is the way to make it work?

Edit:

Of course enterFullScreenMode is for the NSView and I used it on a NSWindow; it's not the view I want to have fullscreen, but the window. I can't find any function for the NSWindow though.