- (void)viewDidLoad
{
    [super viewDidLoad];
    //检测设备朝向使用UIDevice,beginGeneratingDeviceOrientationNotifications方法向通知中心发送朝向信息
    [[UIDevice currentDevice]beginGeneratingDeviceOrientationNotifications];
    //建立通知中心
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(orientationChanged:) name:UIDeviceOrientationDidChangeNotification object:nil];
}

-(void)orientationChanged:(NSNotification *)notification
{
    UIDeviceOrientation orientation=[[UIDevice currentDevice]orientation];
    switch (orientation) {
        case UIDeviceOrientationFaceUp:
            NSLog(@"设备正面朝上");
            break;
            case UIDeviceOrientationFaceDown:
            NSLog(@"设备正面朝下");
            break;
            case UIDeviceOrientationPortrait:
            NSLog(@"设备处于正常朝向,主屏幕按钮在下方");
            break;
            case UIDeviceOrientationPortraitUpsideDown:
            NSLog(@"设备处于纵向,主屏幕按钮在上方");
            break;
            case UIDeviceOrientationLandscapeLeft:
            NSLog(@"设备侧立,左边朝下");
            break;
            case UIDeviceOrientationLandscapeRight:
            NSLog(@"设备侧立,右边朝下");
            break;
        default:
            break;
    }
}

附:检测手机版本信息使用的也是UIDevice.

    //获取硬件信息
    UIDevice *device=[UIDevice currentDevice];
    //输出版本号
    NSLog(@"%@",device.systemVersion);