iOS 判断iphone ipad 系统版本

最常用的方法是<pre name="code" class="objc"><pre name="code" class="objc">[[[UIDevice currentDevice] systemVersion] floatValue];

#define ScreenWidth  ([[UIScreen mainScreen] bounds].size.width)#define ScreenHeight ([[UIScreen mainScreen] bounds].size.height) #define iOS8 ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0)#define iOS7 ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)#define iOS6 ([[[UIDevice currentDevice] systemVersion] floatValue] >= 6.0) #define isPad   (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad   ? YES : NO)#define isPhone (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone ? YES : NO)#define isRetina ([[UIScreen mainScreen] scale] > 1 ? YES : NO)