Hello, I'm a Java/PHP programmer, and I've started programming in Objective-C for Mac OSX. I've understood the MVC pattern for programming user interfaces with Cocoa, but I'm very confused about the SDK to manage filesystem, images, and so on... I've a quite stupid problem but I cannot find an easy solution. What I need is: 1. Load an image from a file 2. Check the size (width and height) and do some stuffs... 3. Crop this image in squares 4. Save each square in a new image file (PNG). I cannot understand how to achieve point 3 and what kind of object I have to use, NSImage? CIImage? CGImage? Any suggestment will be appreciated. Thanks a lot.