IOS 特定于设备的开发：获取和使用设备姿势（通过手机方向控制3d物体显示）

利用设备的机载陀螺仪可以实现，当你旋转手机屏幕时，里面的画面不会随着视图更新而移动，以平衡物理运动。

下面例子利用少量简单的几何变换执行该操作。他建立一个运动管理器，订阅设备运动更新，然后基于运动管理器返回的摇晃，前倾和左右摇摆的角度应用图像变换。

@implementation TestBedViewController
{
    CMMotionManager *motionManager;
    UIImageView *imageView;
}

- (void) shutDownMotionManager
{
    NSLog(@"Shutting down motion manager");
    [motionManager stopDeviceMotionUpdates];
    motionManager = nil;
}

- (void) establishMotionManager
{
    if (motionManager)
        [self shutDownMotionManager];
    
    NSLog(@"Establishing motion manager");
    
    // Establish the motion manager
    motionManager = [[CMMotionManager alloc] init];
    if (motionManager.deviceMotionAvailable)
        [motionManager
         startDeviceMotionUpdatesToQueue:[NSOperationQueue currentQueue]
         withHandler: ^(CMDeviceMotion *motion, NSError *error) {
             CATransform3D transform;
             transform = CATransform3DMakeRotation(motion.attitude.pitch, 1, 0, 0);
             transform = CATransform3DRotate(transform, motion.attitude.roll, 0, 1, 0);
             transform = CATransform3DRotate(transform, motion.attitude.yaw, 0, 0, 1);
             imageView.layer.transform = transform;
         }];
}

- (void) viewDidAppear: (BOOL) animated
{
    NSString *imageName = IS_IPAD ? @"iPadArt.png" : @"iPhoneArt.png";
    UIImage *image = [UIImage imageNamed:imageName];
    imageView = [[UIImageView alloc] initWithImage:image];
    imageView.center = RECTCENTER(self.view.bounds);
    [self.view addSubview:imageView];
}

- (void) loadView
{
    [super loadView];
    self.view.backgroundColor = [UIColor whiteColor];
}