autolayout

可用网址：

 关于autolayout不错的文章  

 http://blog.csdn.net/ysy441088327/article/details/12558097

 http://www.cocoachina.com/industry/20131203/7462.html

http://www.cocoachina.com/ios/20140912/9604.html

http://www.raywenderlich.com/50319/beginning-auto-layout-tutorial-in-ios-7-part-2

iOS Human Interface Guidelines  

（https://developer.apple.com/library/ios/DOCUMENTATION/UserExperience/Conceptual/MobileHIG/Introduction/Introduction.html）