转载URL：http://stackoverflow.com/questions/7848766/how-can-we-programmatically-detect-which-ios-version-is-device-running-on



Best current version, without need to deal with numeric search within NSString is to define macros(See original answer: Check iPhone iOS Version)

Those macros do exist in github, see:https://github.com/carlj/CJAMacros/blob/master/CJAMacros/CJAMacros.h

Like this:

#define SYSTEM_VERSION_EQUAL_TO(v)                  ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedSame)#define SYSTEM_VERSION_GREATER_THAN(v)              ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedDescending)#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(v)  ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedAscending)#define SYSTEM_VERSION_LESS_THAN(v)                 ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)#define SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(v)     ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedDescending)


and use them as below:

if (SYSTEM_VERSION_LESS_THAN(@"5.0")) {
    // code here}if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"6.0")) {
    // code here}