ios - 锁定 iOS 相机曝光崩溃

Question

我有以下代码:

-(void) startCameraCapture {
    // start capturing frames
    // Create the AVCapture Session
    session = [[AVCaptureSession alloc] init];

    // create a preview layer to show the output from the camera
    AVCaptureVideoPreviewLayer *previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:session];
    // Specify that the video should be stretched to fill the layer’s bounds.
    previewLayer.videoGravity = AVLayerVideoGravityResize;

    //previewView.frame = CGRectMake(126.0, 164.0, 64.0, 75.0);


    previewLayer.frame = previewView.frame;
    [previewView.layer addSublayer:previewLayer];

    // Get the default camera device
    AVCaptureDevice* camera = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    // get the current settings
    [appDelegate loadSettings];
    [session startRunning];     
}

有没有办法可以锁定相机设备的曝光，只允许屏幕调整到特定亮度？

抱歉，如果我问得不对。

谢谢。

编辑:

我尝试添加:

[camera setExposureModeCustomWithDuration:CMTimeMake(1,1) ISO:100 completionHandler:nil];

但这只会导致应用在该行崩溃。

Answer 1

根据 Apple 的文档:

如果调用此方法时未首先使用 lockForConfiguration 获得对接收器的独占访问权限，则会抛出 NSGenericException 异常:。

所以在前面加上这一行:

[camera lockForConfiguration:nil];