当前设备的系统版本号

- (void)viewDidLoad {

[super viewDidLoad];

NSString * systermVersion = [[UIDevice currentDevice] systemVersion];

NSString * systermVersionName = [[UIDevice currentDevice] systemName];

NSLog(@"systermVersion = %@",systermVersion);

NSLog(@"systermVersionName = %@",systermVersionName);

//    2015-12-15 14:28:57.629 试炼[19620:3028281] systermVersion = 9.0

//    2015-12-15 14:28:57.632 试炼[19620:3028281] systermVersionName = iPhone OS

}