When I last undertook to teach myself Cocoa, about a year and a half ago, one technique in particular seemed poorly documented, mysterious, and generally lacking intelligible example that didn’t involve pulling out advanced trigonometry books. If, by chance, you are searching on these terms and you should find my site here, I should hope that I make your life a goodly bit easier by giving you a simple example with concrete explanations. Thanks to the proliferation of people liking Mac OSX, a great many tutorials on the topic have surfaced, but as you’re asking “How do I turn my image about 90 degrees” these tutorials are a bit “heavy” and confusing.