ios - didRotateFromInterfaceOrientation 在 iOS 8 中被弃用

Question

自 iOS 8.0 起，函数 didRotateFromInterfaceOrientation 已弃用，我现在不知道如何更改 AVCaptureVideoPreviewLayer 的方向适本地。

根据 "interfaceOrientation" is deprecated in iOS 8, How to change this method Objective C ，我有以下工作代码来获取基于 statusBarOrientation 的 AVCaptureVideoOrientation:

- (AVCaptureVideoOrientation)getOrientation {
    // Translate the orientation
    switch ([[UIApplication sharedApplication] statusBarOrientation]) {
        case UIInterfaceOrientationPortrait:
            return AVCaptureVideoOrientationPortrait;
        case UIInterfaceOrientationPortraitUpsideDown:
            return AVCaptureVideoOrientationPortraitUpsideDown;
        case UIInterfaceOrientationLandscapeLeft:
            return AVCaptureVideoOrientationLandscapeLeft;
        case UIInterfaceOrientationLandscapeRight:
            return AVCaptureVideoOrientationLandscapeRight;
        default:
            return AVCaptureVideoOrientationPortrait;
    }
}

当方向改变时，我需要调用以下函数:

[self.videoPreviewLayer.connection setVideoOrientation:[self getOrientation]];

但是我不知道放哪里合适。

尝试 1

由于 didRotateFromInterfaceOrientation 已被弃用并且 Apple 建议使用 viewWillTransitionToSize:withTransitionCoordinator:，这似乎是很自然的尝试:

- (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator
{
    [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator];
    [coordinator animateAlongsideTransition:nil completion:^(id<UIViewControllerTransitionCoordinatorContext>  _Nonnull context) {
        [self.videoPreviewLayer.connection setVideoOrientation:[self getOrientation]];
    }];
}

但如果 UIViewController 正在显示，则不会调用此函数(似乎是基于 "viewWillTransitionToSize:" not called in iOS 9 when the view controller is presented modally 的已知错误)。即使解决了这个错误，还有另一个问题:方向更改不等同于大小更改。例如，如果 View 显示为 UIModalPresentationFormSheet，如下所示，

SecondViewController *vc = [[SecondViewController alloc] init];
vc.view.backgroundColor = [UIColor greenColor];
vc.modalPresentationStyle = UIModalPresentationFormSheet;
[self presentViewController:vc animated:true completion:nil];

在 iPad 的横向和纵向模式下呈现的 View 大小相同:

因此，我不能简单地使用 viewWillTransitionToSize。

尝试 2

我注意到 UIDeviceOrientationDidChangeNotification 没有被弃用。伟大的!我尝试注册一个通知:

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    // Some other code to set up the preview layer 
    // ...

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

- (void)viewWillDisappear:(BOOL)animated
{
    [[UIDevice currentDevice] endGeneratingDeviceOrientationNotifications];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIDeviceOrientationDidChangeNotification object:nil];
}

- (void)deviceOrientationDidChange:(NSNotification *)notification {
    [self.videoPreviewLayer.connection setVideoOrientation:[self getOrientation]];
}

这几乎可以正常工作，而且已经关闭了!问题是，当我收到设备方向更改通知时，旋转 View 的动画可能会开始，也可能不会。或者换句话说，返回值 [[UIApplication sharedApplication] statusBarOrientation] 可能不正确，如果设备已经上下旋转但动画仍在挂起。

我不知道还能尝试什么 :( 有什么想法吗？

Answer 1

以下应该能够在 swift 2.1 中正确处理视频预览的方向:

override func viewWillAppear(animated: Bool) {
    super.viewDidLoad()

    NSNotificationCenter.defaultCenter().addObserver(self,
        selector: Selector("deviceOrientationDidChange:"),
        name: UIDeviceOrientationDidChangeNotification,
        object: nil)
}

override func viewDidDisappear(animated: Bool) {
    NSNotificationCenter.defaultCenter().removeObserver(self)
    super.viewDidDisappear(animated)
}

func deviceOrientationDidChange(sender: AnyObject) {
    let deviceOrientation = UIDevice.currentDevice().orientation;
    switch (deviceOrientation)
    {
    case .Portrait:
       previewLayer.connection.videoOrientation = .Portrait
    case .LandscapeLeft:
       previewLayer.connection.videoOrientation = .LandscapeRight
    case .LandscapeRight:
        previewLayer.connection.videoOrientation = .LandscapeLeft
    case .PortraitUpsideDown:
       previewLayer.connection.videoOrientation = .PortraitUpsideDown
    default:
        break
    }
}