Question

我已经按照教程指导了一个定制但简单的相机应用程序，几乎完全符合我想要的使用需求。我实际上有两个问题需要改变，但我现在将重点关注第一个问题。

以下代码允许使用后置摄像头，但我基本上需要对其进行更改，以便我可以使用前置摄像头。我还会在这里链接我从中获取的视频给予他们的信任，然后我按照其中一位评论者所说的使用前置摄像头但答案根本没有帮助。

https://www.youtube.com/watch?v=Xv1FfqVy-KM

我根本不擅长编码，而是努力学习。任何帮助，将不胜感激！非常感谢。

@interface ViewController ()

@end

@implementation ViewController

AVCaptureSession *session;
AVCaptureStillImageOutput *StillImageOutput;

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)viewWillAppear:(BOOL)animated {

    session = [[AVCaptureSession alloc] init];

    [session setSessionPreset:AVCaptureSessionPresetPhoto];

    AVCaptureDevice *inputDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    NSError *error;

    AVCaptureDeviceInput *deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:&error];



    if ([session canAddInput:deviceInput]) {

        [session addInput:deviceInput];

    }



    AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];

    [previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];

    CALayer *rootLayer = [[self view] layer];

    [rootLayer setMasksToBounds:YES];

    CGRect frame = frameforcapture.frame;



    [previewLayer setFrame:frame];



    [rootLayer insertSublayer:previewLayer atIndex:0];





    StillImageOutput = [[AVCaptureStillImageOutput alloc] init];

    NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG, AVVideoCodecKey, nil];

    [StillImageOutput setOutputSettings:outputSettings];



    [session addOutput:StillImageOutput];



    [session startRunning];

}



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

- (IBAction)takephoto:(id)sender {

    AVCaptureConnection *videoConnection = nil;

    for (AVCaptureConnection *connection in StillImageOutput.connections) {
        for (AVCaptureInputPort *port in [connection inputPorts ]) {
            if ([[port mediaType] isEqual:AVMediaTypeVideo]) {
                videoConnection = connection;
                break;
            }
        }
    }
    [StillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
        if (imageDataSampleBuffer != NULL) {
            NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
            UIImage *image = [UIImage imageWithData:imageData];
            imageView.image = image;
        }
    }];
}

@end

Answer 1

此代码返回给定媒体类型的默认设备的AVCaptureDevice实例。

AVCaptureDevice *inputDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

将此代码更改为

....
AVCaptureDevice *inputDevice = nil;
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for(AVCaptureDevice *camera in devices) {
    if([camera position] == AVCaptureDevicePositionFront) { // is front camera  
        inputDevice = camera;
        break;
    }
}
......

Answer 2

- (IBAction)btnCameraClicked:(id)sender {

    AVCaptureDevicePosition desiredPosition;
    if (isUsingFrontFacingCamera)
        desiredPosition = AVCaptureDevicePositionBack;
    else
        desiredPosition = AVCaptureDevicePositionFront;

    for (AVCaptureDevice *d in [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]) {
        if ([d position] == desiredPosition) {
            [[previewLayer session] beginConfiguration];
            AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:d error:nil];
            for (AVCaptureInput *oldInput in [[previewLayer session] inputs]) {
                [[previewLayer session] removeInput:oldInput];
            }
            [[previewLayer session] addInput:input];
            [[previewLayer session] commitConfiguration];
            break;
        }
    }
    isUsingFrontFacingCamera = !isUsingFrontFacingCamera;
}

//在.h文件中声明

AVCaptureVideoPreviewLayer *previewLayer;
BOOL isUsingFrontFacingCamera;

Objective-C AVCaptureDevice前置摄像头

2 个答案: