High-quality graphics are an important part of all iOS applications. The simplest (and most efficient) way to create an application is to use prerendered images together with the standard views and controls of the UIKit framework and let the system do the drawing. However, there may be situations where you need to go beyond simple graphics. In those situations, you can use the following technologies to manage your application’s graphical content:
- Core Graphics (also known as Quartz) handles native 2D vector- and image-based rendering.
- Core Animation (part of the Quartz Core framework) provides advanced support for animating views and other content.
- Core Image provides advanced support for manipulating video and still images.
- OpenGL ES and GLKit provide support for 2D and 3D rendering using hardware-accelerated interfaces.
- Core Text provides a sophisticated text layout and rendering engine.
- Image I/O provides interfaces for reading and writing most image formats.
- The Assets Library framework provides access to the photos and videos in the user’s photo library.
Quartz 2D编程指南
http://mechenwei.iteye.com/blog/1254689
（译）OpenGL ES2.0 – Iphone开发指引
http://www.cnblogs.com/andyque/archive/2011/08/08/2131019.html
西蒙iPhone-OpenGL ES 中文教程专题