I am reading COCOA PROGRAMMING FOR MAC OS X by Aaron Hillegass (and learning a LOT by the way). I am attempting one of the challenges in the book, that is, making a window resize itself so it is always twice as wide as it is high. The challenge was to make a "helper" object that would take on the delegate duties for a NSWindow. I've done that and even made the object react when the window is resized. I cannot, however, seem to get the dimensions of the newly resized window in order to complete the task. I've tried a few different things, and I keep getting the same (obviously wrong) dimensions. The height is 0 and the width is some large number over a billion. The delegate method that I'm using is -(NSSize)windowWillResize:_(NSWindow *)sender toSize:_(NSSize)frameSize and I've tried to access the size using sender.frame.width, frameSize.width and theWindow.frame.width. Please tell me how I can get this information accurately.