UIWindow & UIWindowLevel笔记
http://www.cnblogs.com/smileEvday/archive/2012/03/27/2420362.html
demo:https://github.com/pandabo1985/IOS_App_Prac/tree/master/windowDemo
UIView属性学习
http://www.cocoachina.com/newbie/basic/2012/0425/4192.html
demo:https://github.com/pandabo1985/IOS_App_Prac/tree/master/UIViewDemoUIViewControl使用http://blog.csdn.net/mengtnt/article/details/6709930https://github.com/pandabo1985/IOS_App_Prac/tree/master/UIControlViewDemo