Ios 使用AVCaptureSession全屏捕获视频

我需要我的应用程序显示前摄像头正在拍摄的内容的实时预览，并且该视频流的尺寸需要与设备的屏幕大小相匹配

但在预览视图的顶部和底部会出现黑色条。。。

如何捕获和预览具有全屏尺寸的视频？注意，我不想调整视频的大小

下面是我的代码：

session = [[AVCaptureSession alloc] init];
session.sessionPreset = AVCaptureSessionPresetPhoto;

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];

[session addInput:input];

UIView *cameraPreviewView = [[UIView alloc] initWithFrame:self.view.frame] ;
[self.view addSubview:cameraPreviewView];

AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];
[session addOutput:output];

dispatch_queue_t queue = dispatch_queue_create("myQueue", NULL);
[output setSampleBufferDelegate:self queue:queue];

AVCaptureVideoPreviewLayer *cameraPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
cameraPreviewLayer.frame = cameraPreviewView.bounds;

[cameraPreviewView.layer addSublayer:cameraPreviewLayer];
[cameraPreviewLayer setBackgroundColor:[[UIColor blackColor] CGColor]];
[cameraPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspect];

[session startRunning];

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尝试“NSLOG”cameraPreviewLayer和UIView的框架；我认为这就是罪魁祸首：cameraPreviewLayer.frame=cameraPreviewView.bounds…