iOS设备快速旋转180度会导致相机倒置 [英] Quick 180 rotation of iOS Device results in the camera viewing upside-down

问题描述

我已经实现了以下代码，根据 UIInterfaceOrientation 更改 AVCaptureVideoSession 的方向：

I've implemented the code below to change the orientation of an AVCaptureVideoSession based upon the UIInterfaceOrientation:

- (AVCaptureVideoOrientation)interfaceOrientationToVideoOrientation:(UIInterfaceOrientation)orientation {
    switch (orientation) {
        case UIInterfaceOrientationPortrait:
            return AVCaptureVideoOrientationPortrait;
        case UIInterfaceOrientationPortraitUpsideDown:
            return AVCaptureVideoOrientationPortraitUpsideDown;
        case UIInterfaceOrientationLandscapeLeft:
            return AVCaptureVideoOrientationLandscapeLeft;
        case UIInterfaceOrientationLandscapeRight:
            return AVCaptureVideoOrientationLandscapeRight;
        default:
            break;
    }
    NSLog(@"Warning - Didn't recognise interface orientation (%ld)",(long)orientation);
    return AVCaptureVideoOrientationPortrait;
}

此代码几乎完美无缺。但是，出现的一个问题是，如果您快速将iOS设备旋转180度，相机将显示为颠倒。

This code works almost perfectly. However, one problem that occurs is that if you quickly rotate the iOS device 180 degrees, the camera will be shown upside down.

以下是轮换前相机视图的样子：

Here's what the camera view looks like before the rotation:

以下是轮换后的样子：

此外，这是我的 viewDidLayoutSubviews 的实现：

Additionally, here is my implementation of viewDidLayoutSubviews:

- (void)viewDidLayoutSubviews {

    [super viewDidLayoutSubviews];

    previewLayer.frame = self.view.bounds;

    self.view.translatesAutoresizingMaskIntoConstraints = NO;
    previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    [self.view.layer addSublayer:previewLayer];

    if (previewLayer.connection.supportsVideoOrientation) {
        previewLayer.connection.videoOrientation = [self interfaceOrientationToVideoOrientation:[UIApplication sharedApplication].statusBarOrientation];
    }
}

有没有人知道为什么相机视图会这种180度旋转发生时会颠倒吗？

Does anyone have an idea of why the camera view would be upside down when this 180-degree rotation occurs?

推荐答案

我之前有同样的问题解决了我的问题。

I had the same issue before here what solved my issue.

我声明了一个全局变量：

I declared a global variable:

@interface YourViewController ()
{
    ...
    UIDevice *iOSDevice;
}

..

@end

在实现（.m文件）下，我在 -viewWillAppear 下声明了NSNotification观察者，如：

Under implementation (.m file) i declared NSNotification observer under -viewWillAppear like:

@implementation YourViewController

-(void)viewWillAppear:(BOOL)animated
{
    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];

    [[NSNotificationCenter defaultCenter] addObserver:self  selector:@selector(orientationChanged:) name:UIDeviceOrientationDidChangeNotification  object:[UIDevice currentDevice]];

}

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

- (void)orientationChanged:(NSNotification *)notification
{
    iOSDevice = notification.object;

    previewLayer.connection.videoOrientation = [self interfaceOrientationToVideoOrientation];

    //or

    [self setAutoVideoConnectionOrientation:YES];

}

我做了一个函数，返回复制的当前方向设备如：

I made a function that returns the orientation of the copied current device like:

在我的 -interfaceOrientationToVideoOrientation 方法中获取战利品，它会转换 iOSDevice .orientation 进入 AVCaptureVideoOrientation 与你的相同......

Take a loot at my -interfaceOrientationToVideoOrientation method, it converts the iOSDevice.orientation into AVCaptureVideoOrientation same with what you have there..

（在我的情况下，我需要以下功能，但看看它可能因某些原因对您有用）

(In my case i needed this functions below, but take a look at it might be useful to you for some reason)

- (AVCaptureVideoOrientation)interfaceOrientationToVideoOrientation
{
    switch (iOSDevice.orientation) {

        case UIInterfaceOrientationPortraitUpsideDown:

            return AVCaptureVideoOrientationPortraitUpsideDown;

        case UIInterfaceOrientationLandscapeLeft:

            return AVCaptureVideoOrientationLandscapeLeft;

        case UIInterfaceOrientationLandscapeRight:

            return AVCaptureVideoOrientationLandscapeRight;

        default:
        case UIDeviceOrientationPortrait:
            return AVCaptureVideoOrientationPortrait;
    }
}

- (AVCaptureConnection *)setAutoVideoConnectionOrientation:(BOOL)status
{
    AVCaptureConnection *videoConnection = nil;

    //This is for me
    //for (AVCaptureConnection *connection in stillImageOutput.connections) {

    //This might be for you
    for (AVCaptureConnection *connection in previewLayer.connection) {

        for (AVCaptureInputPort *port in [connection inputPorts])
        {
            if ([[port mediaType] isEqual:AVMediaTypeVideo])
            {
                videoConnection = connection;

                if (status == YES)
                {
                    [videoConnection setVideoOrientation:[self interfaceOrientationToVideoOrientation]];
                }
                else
                {
                    [videoConnection setVideoOrientation:AVCaptureVideoOrientationPortrait];
                }
            }
            if (videoConnection)
            {
                break;
            }
        }
    }
    return videoConnection;
}

修改

默认方向：您需要检查当前方向。

For default orientation: You need to check the "current" orientation.

- (void)viewDidLoad
{
    [super viewDidLoad];

    // assuming you finish setting the `previewLayer`

    ..
    // after all of that code, when the view is ready for displaying
    // if you implemented this approach the best thing to do is:

    // set this 
    iOSDevice = [UIDevice currentDevice];

    // then call 
    previewLayer.connection.videoOrientation = [self interfaceOrientationToVideoOrientation];
    // to update the `previewLayer.connection.videoOrientation ` for default orientation        

}

注意：

使用 NSNotificationCenter 让设备的轮换先解决触发..

Using NSNotificationCenter let the rotation of the device to be settled first before triggered..

希望这对你有帮助..

Hope this have help you..

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