#define isRetina ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(640, 960), [[UIScreen mainScreen] currentMode].size) : NO)
#define iPhone5 ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(640, 1136), [[UIScreen mainScreen] currentMode].size) : NO)
#define isPad (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
原文:http://www.cnblogs.com/huangpengfei/p/3605345.html