You’ve seen me endorse Cocos2D, and I’ve posted some tutorials on Core Animation, but for the most part I’ve stayed away from posting about Core Graphics. The reason for this is so much can be done elsewhere, but there are times as an iPhone developer when you will have to drop down to the lower levels of Core Graphics, there are also some time saving functions in Core Graphics that you will want to be familiar with.
For those unfamiliar with Core Graphics, Core Graphics is defined by Apple as:
"a C-based API that is based on the Quartz advanced drawing engine. It provides low’level lightweight 2D rendering"
It is used for:
"path-based drawing, transformations, color management, offscreen rendering, patterns, gradients and shadings, image data management, image creation, masking, and PDF documentation creation, display and parsing."
Here’s a list of resources that should help you to learn in using Core Graphics:
Apple’s Mac Getting Started With Graphics & Animation – Useful, but Core Image, Core Video, and Quicktime do not exist on the iPhone.
Useful Core Graphics Functions – Nice selection of functions in Core Graphics that can be used to speed things up.
Converting Points And Rectangles To Strings And Back – Some useful functions for when you’re working with Core Graphics points and rectangles.
Exploring iPhone Graphics Part 1 – Basic shapes tutorial repeated all over the place, this is the best one that I’ve seen.
Exploring iPhone Graphics Part 2 – Very good beginners animation tutorial with Core Graphics.
The best book for learning Core Graphics I’ve read is Quartz 2D Graphics for Mac OS X Developers which goes into many topics I could not find much online training for. As you might expect from the title the book is not iPhone specific.
These are the resources that I found around that were most useful. I found the basic shapes with Core Graphics tutorial repeated many times, so I only posted the best one. This should be enough to get you going and understanding Apple’s examples with Core Graphics.