how can I check if a Gyroscope is present on iOS device?

- (BOOL) isGyroscopeAvailable
{
#ifdef __IPHONE_4_0
    CMMotionManager *motionManager = [[CMMotionManager alloc] init];
    BOOL gyroAvailable = motionManager.gyroAvailable;
    [motionManager release];
    return gyroAvailable;
#else
    return NO;
#endif

}