Xcode 调用OpenCV系统错误汇总

错误和异常Errors and exceptions

（下面两条来自https://www.timpoulsen.com/2018/acquiring-images.html）

1. As with reading still images, OpenCV does not offer proper exception handling when reading from a video source. If you specify a source that doesn't exist, you'll get an error like the following

out device of bound (0-0): 1 opencv: camera failed to properly initialize!

(To create the preceding error, I used camera = cv2.VideoCapture(1) and since my laptop has just one camera, camera 1doesn't exist.)

2. It's important to release the video source properly when you're done by calling the release() method. Failing to do so can leave your camera unusable. Below is an example of the error you get attempting to use the built-in camera on a Mac that was not released properly before.

OpenCV: error in [AVCaptureDeviceInput initWithDevice:error:]OpenCV: Cannot Use FaceTime HD Camera (Built-in)OpenCV: camera failed to properly initialize!

If you end up in this state, you may have to restart your computer to recover. On the Mac, you can use the following command rather than restarting:

sudo killall VDCAssistant

3. Xcode中没有访问摄像头的权限，尽管在plist中加入了权限请求，依然可能不行。粗暴一点就是2的办法，另外一种办法，在termial中运行编译好的程序，然后赋予termial调用权限，访问正常，但是调试麻烦，可到Xcode attach到进程进行调试。

（https://stackoverflow.com/questions/56084303/opencv-command-line-app-cant-access-camera-under-macos-mojave）