iphone - iOS 根据设备方向切换 View Controller

Question

我正在开发一个增强现实应用程序，到目前为止一切正常，我需要两种不同类型的可视化(AR 和 map )，具体取决于设备方向。特别是当设备处于横向模式时，应用程序应该使用 LandscapeViewController，而当设备的方向是“面朝上”时，它应该使用另一个 Controller (名为 faceUpViewController )。我试过用两个简单的 View Controller 来做，效果很好。当 LandscapeViewController 使用 AR Controller 时，就会出现问题。 View 完全是白色的，我不明白为什么。这两个 Controller 都被 Root View Controller “包含”。我通过编码来做所有事情，所以没有 nib 文件。这是代码:

RootViewController.m

- (void)viewDidLoad
{
    [super viewDidLoad];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(deviceOrientationDidChange:) name:UIDeviceOrientationDidChangeNotification object:nil];
    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
}

- (void)deviceOrientationDidChange:(NSNotification *)notification{

    UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];

    if (orientation == UIDeviceOrientationLandscapeLeft) {
        if (self.landscapeViewController.view.superview == nil) {
            if (self.landscapeViewController == nil) {
                LandscapeViewController *lvc = [[LandscapeViewController alloc] init];
                self.landscapeViewController = lvc;
                [lvc release];
            }
            [self.faceUpViewController.view removeFromSuperview];
            [self.view addSubview:self.landscapeViewController.view];
        }
    }

    if (orientation == UIDeviceOrientationFaceUp) {
        if (self.faceUpViewController.view.superview == nil) {
            if (self.faceUpViewController == nil) {
                FaceUpViewController *fvc = [[FaceUpViewController alloc] init];
                self.faceUpViewController = fvc;
                [fvc release];
            }
            [self.landscapeViewController.view removeFromSuperview];
            [self.view addSubview:self.faceUpViewController.view];
        }
    }

}

@end

LandscapeViewController.m

// Implement loadView to create a view hierarchy programmatically, without using a nib.
- (void)loadView
{
    UIView *landscapeView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 1024, 768)];
    landscapeView.backgroundColor = [UIColor yellowColor];
    self.view = landscapeView;
    [landscapeView release];

    ARController *arC = [[ARController alloc] initWithViewController:self];
    arC.landscapeViewController = self;
    self.arController = arC;
    [arC release];
}

//When the view appear present the camera feed
- (void)viewDidAppear:(BOOL)animated { 
    [super viewDidAppear:animated]; 
    [_arController presentModalARControllerAnimated:NO];
}

FaceUpViewController.m

- (void)loadView
{
    UIView *faceUpView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 1024, 768)];
    faceUpView.backgroundColor = [UIColor blueColor];
    self.view = faceUpView;
    [faceUpView release];
}

ARController.m 非常简单的版本

- (id) initWithViewController:(UIViewController *)theView{

    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {

        self.rootController = theView; 

        //Retrieve screen bounds
        CGRect screenBounds = [[UIScreen mainScreen] bounds]; 

        UIView *overlaidView = [[UIView alloc] initWithFrame: screenBounds];
        self.overlayView =  overlaidView;
        [overlaidView release];
        self.rootController.view = overlayView;

        // Initialise the UIImagePickerController 
        UIImagePickerController *picker= [[UIImagePickerController alloc] init];
        self.pickerController = picker;
        [picker release];

        self.pickerController.sourceType = UIImagePickerControllerSourceTypeCamera; 
        self.pickerController.cameraViewTransform = CGAffineTransformScale(
                                                                           self.pickerController.cameraViewTransform, 1.0f, 1.12412f);

        self.pickerController.showsCameraControls = NO; 
        self.pickerController.navigationBarHidden = YES; 
        self.pickerController.cameraOverlayView = _overlayView;
    }

    return self;
}

- (void)presentModalARControllerAnimated:(BOOL)animated{
    [self.rootController presentModalViewController:[self pickerController] animated:animated]; 
    self.overlayView.frame = self.pickerController.view.bounds;
}

@end

我再说一遍，我所做的一切都是通过编码来完成的，而不需要 nib 文件。
我真的很感激任何建议!
谢谢

Answer 1

像您在此处所做的那样添加和删除“子” View Controller 的 View 的主要问题是 View Controller 生命周期方法( viewWillAppear: ， viewDidAppear: 等)永远不会被您的 child 调用 View Controller 。像 UINavigationController 这样的容器和 UITabBarController一直都知道如何将这些方法适本地委派给他们的 child ，但是 UIViewController在 iOS 5 之前，没有正式支持将 View Controller 嵌套在您自己的自定义容器下的能力。这是可能的，但要做到这一点需要做更多的工作。

如果您想坚持添加和删除 subview 的方法，您有两种选择:

需要 iOS 5+，调用 addChildViewController: , removeFromParentViewController ,transitionFromViewController:toViewController:duration:options:animations:completion: ,willMoveToParentViewController: ， 和didMoveToParentViewController:如 Implementing a Container View Controller 中所述UIViewController 的部分类引用。

要支持较旧的 iOS 版本，您必须重写 UIViewController 的许多方法。类并将这些调用手动委托(delegate)给您的 subview Controller ，以使它们按预期运行。我会特别注意 UIViewController 中标题为“响应 View 事件”和“响应 View 轮换事件”的部分。类引用。

支持 iOS 5 之前的另一种方法是使用 presentModalViewController:animated: 呈现您的 subview Controller 。而不是将它们的 View 作为 subview 添加到容器中。 Apple 在 View Controller Programming Guide for iOS 的 Creating an Alternate Landscape Interface 部分中描述了这种方法。 .这种方法的优点是您的 subview Controller 被官方支持为 View Controller 层次结构的一等成员，因此 UIKit 将自动适本地管理它们的生命周期。您不必手动覆盖和委托(delegate)所有这些方法。