CAMARA预览不显示在正确的时候，开发一个自定义相机应用程序的iOS从AV基础框架工作？

我正在用xcode 5为ios 7开发一个定制的摄像头应用程序。我有一个类，其中视图控制器如下

    #import "ADMSImageUploader.h"
#import "ADMSViewController.h"

@interface ADMSImageUploader ()

@end

@implementation ADMSImageUploader

AVCaptureVideoPreviewLayer *captureVideoPreviewLayer;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    FrontCamera = NO;
    [self initializeCamera];

}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (void)viewDidAppear:(BOOL)animated {


}

//AVCaptureSession to show live video feed in view
- (void) initializeCamera {
    session = [[AVCaptureSession alloc] init];
    session.sessionPreset = AVCaptureSessionPresetPhoto;

    captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
    [self.imagePreview.layer setMasksToBounds:YES];

    //    CGSize landscapeSize;
    //    landscapeSize.width = self.imagePreview.bounds.size.width;
    //    landscapeSize.height = self.view.bounds.size.width;

    //CGRect rect=[[UIScreen mainScreen]bounds];

    captureVideoPreviewLayer.frame = CGRectMake(0.0, 0.0, self.imagePreview.frame.size.width, self.imagePreview.frame.size.height);
    connection = captureVideoPreviewLayer.connection;
    orientation = AVCaptureVideoOrientationLandscapeRight;
    //connection.videoOrientation = AVCaptureVideoOrientationLandscapeRight;
    [captureVideoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];

//    if ([[UIDevice currentDevice] orientation] == UIInterfaceOrientationPortrait ) {
//        captureVideoPreviewLayer.frame = CGRectMake(0.0, 0.0, self.imagePreview.frame.size.width, self.imagePreview.frame.size.height);
//        connection = captureVideoPreviewLayer.connection;
//        orientation = AVCaptureVideoOrientationPortrait;
//        //connection.videoOrientation = AVCaptureVideoOrientationLandscapeRight;
//        [captureVideoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
//        
//    }else{
//        captureVideoPreviewLayer.frame = CGRectMake(0.0, 0.0, self.imagePreview.frame.size.width, self.imagePreview.frame.size.height);
//        connection = captureVideoPreviewLayer.connection;
//        orientation = AVCaptureVideoOrientationLandscapeRight;
//        //connection.videoOrientation = AVCaptureVideoOrientationLandscapeRight;
//        [captureVideoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
//
//    }

    [self.imagePreview.layer addSublayer:captureVideoPreviewLayer];


    NSArray *devices = [AVCaptureDevice devices];
    AVCaptureDevice *frontCamera;
    AVCaptureDevice *backCamera;

    for (AVCaptureDevice *device in devices) {

        NSLog(@"Device name: %@", [device localizedName]);

        if ([device hasMediaType:AVMediaTypeVideo]) {

            if ([device position] == AVCaptureDevicePositionBack) {
                NSLog(@"Device position : back");
                backCamera = device;
            }
            else {
                NSLog(@"Device position : front");
                frontCamera = device;
            }
        }
        else{
            if (!([device position] == AVCaptureDevicePositionBack)) {
                UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Cannot take photos using rear camera"
                                                                message:@"Your device doesnot support this feature."
                                                               delegate:nil
                                                      cancelButtonTitle:@"OK"
                                                      otherButtonTitles:nil];
                [alert show];

            }
        }
    }

    if (!FrontCamera) {
        NSError *error = nil;
        AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:backCamera error:&error];
        if (!input) {
            NSLog(@"ERROR: trying to open camera: %@", error);
        }
        [session addInput:input];
    }

    if (FrontCamera) {
        NSError *error = nil;
        AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:frontCamera error:&error];
        if (!input) {
            NSLog(@"ERROR: trying to open camera: %@", error);
        }
        [session addInput:input];
    }

    _stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
    NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys: AVVideoCodecJPEG, AVVideoCodecKey, nil];
    [_stillImageOutput setOutputSettings:outputSettings];

    [session addOutput:_stillImageOutput];

    [session startRunning];
}

- (BOOL)shouldAutorotate{
     return YES;
    }


//-(void)openCamera:(NSString *)dealerId:(NSString *)inventoryId
//{
//    
//}
- (void)viewWillAppear:(BOOL)animated
{
    [self.navigationController setNavigationBarHidden:YES animated:animated];
    [super viewWillAppear:animated];
    _uploadButtonBehaviour.hidden = YES;
    _discardButtonBehaviour.hidden = YES;
}

- (void)viewWillDisappear:(BOOL)animated
{
    [self.navigationController setNavigationBarHidden:NO animated:animated];
    [super viewWillDisappear:animated];
}

- (NSUInteger)supportedInterfaceOrientations;
{
    return UIInterfaceOrientationMaskLandscape;
}


- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation;
{

        captureVideoPreviewLayer.frame = CGRectMake(0.0, 0.0,self.imagePreview.frame.size.width,self.imagePreview.frame.size.height);
        [captureVideoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
        connection = captureVideoPreviewLayer.connection;
        [captureVideoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];

        //  connection.videoOrientation = AVCaptureVideoOrientationLandscapeRight;

        [connection setVideoOrientation:AVCaptureVideoOrientationLandscapeRight];


}

-(UIInterfaceOrientation)preferredInterfaceOrientationForPresentation
{
    return UIInterfaceOrientationLandscapeRight;
}

- (IBAction)captureButton:(id)sender {
}

- (IBAction)exitButton:(id)sender {
    [self.navigationController popToRootViewControllerAnimated:YES];
}

- (IBAction)uploadButton:(id)sender {
}

- (IBAction)discardButton:(id)sender {
}
@end

我只想在景观模式下启动此视图控制器。我正在使用导航控制器转到不同的视图控制器

当我的上一个视图控制器处于垂直方向时，相机预览如下所示

当我旋转ios设备以横向移动时，会显示以下摄像头预览。这里的问题是预览图像会被拉伸

当我的上一个视图控制器处于水平方向时，相机预览如下所示。摄影机预览显示为反转。

---

. 我请求你在这个问题上帮助我。

我曾经遇到过同样的问题。我通过检测设备方向，使用CGAffineTransformMakeScale手动旋转捕获的图像来解决这个问题

if ([[UIDevice currentDevice] orientation] == UIDeviceOrientationLandscapeRight) {
    CIImage *c = [[CIImage alloc] initWithImage:imageFromCamera];
    c = [c imageByApplyingTransform:CGAffineTransformTranslate(CGAffineTransformMakeScale(-1, -1), 0, c.extent.size.height)];
    imageFromCamera = [UIImage imageWithCGImage:[[CIContext contextWithOptions:nil] createCGImage:c fromRect:c.extent]];
}

如果旋转不正确，请更改

cGraffineTransformMakeScale

的值

//AVCaptureSession to show live video feed in view
- (void) initializeCamera
{
    session = [[AVCaptureSession alloc] init];
    if ([session canSetSessionPreset:AVCaptureSessionPresetPhoto]) {
        session.sessionPreset = AVCaptureSessionPresetPhoto;
        devicesArray = [AVCaptureDevice devices];
        for (AVCaptureDevice *device in devicesArray){
            if ([device hasMediaType:AVMediaTypeVideo]){
                if ([device position] == AVCaptureDevicePositionBack){
                    NSLog(@"Device name: %@", [device localizedName]);
                    NSLog(@"Device position : back");
                    backCamera = device;
                    backCameraCheck = YES;
                }
            }
        }
        if (backCameraCheck) {
            NSError *error = nil;
            inputDevice = [AVCaptureDeviceInput deviceInputWithDevice:backCamera error:&error];
            if (!inputDevice){
                NSLog(@"ERROR: trying to open camera: %@", error);
            }else{
                [session addInput:inputDevice];
            }
        }else{
            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Cannot take photos using rear camera"
                                                            message:@"Your device doesnot support this feature."
                                                           delegate:nil
                                                  cancelButtonTitle:@"OK"
                                                otherButtonTitles:nil];
            [alert show];
        }
        output = [[AVCaptureVideoDataOutput alloc] init];
        [session addOutput:output];
        captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
        [captureVideoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
        connection = [output connectionWithMediaType:AVMediaTypeVideo];
        connection = captureVideoPreviewLayer.connection;
        if ([[UIDevice currentDevice] orientation] == UIInterfaceOrientationPortrait ) {
            captureVideoPreviewLayer.frame = CGRectMake(0.0, 0.0, self.imagePreview.frame.size.width, self.imagePreview.frame.size.height);
            if ([connection isVideoOrientationSupported]){
                orientation = AVCaptureVideoOrientationPortrait;
                [connection setVideoOrientation:orientation];
            }
        }else{
            NSLog(@"view width = %f %f", self.imagePreview.frame.size.width, self.imagePreview.frame.size.height);
            captureVideoPreviewLayer.frame = CGRectMake(0.0, 0.0, self.imagePreview.frame.size.height,self.imagePreview.frame.size.width);
            if ([connection isVideoOrientationSupported]){
                orientation = AVCaptureVideoOrientationLandscapeRight;
                [connection setVideoOrientation:orientation];
            }
        }
        [self.imagePreview.layer setMasksToBounds:YES];
        [self.imagePreview.layer addSublayer:captureVideoPreviewLayer];


        _stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
        NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys: AVVideoCodecJPEG, AVVideoCodecKey, nil];
        [_stillImageOutput setOutputSettings:outputSettings];
        [session addOutput:_stillImageOutput];
        [session startRunning];
    }else {
        // Handle the failure.
    }
}