1.
http://news.qiyeku.com/news_837979.html
2. opengl
+ (Class)layerClass { return [CAEAGLLayer class]; }
http://www.cnblogs.com/salam/p/5113572.html
http://blog.csdn.net/wanglixin1999/article/details/51792505
http://www.cnblogs.com/bigly/p/5806186.html