上周打开FaceTime，发现摄像头用不了，出现“ There is no connected camera”的提示。
网上查了下，没怎么细看，直接咨询了Apple服务，顺利解决。下面是对话截图和具体步骤：
对话截图
- Shut down your Mac.
- Found Command(⌘), Option, P, and R on your keyboard.
- Turn on your Mac.
- Press and hold the Command-Option-P-R keys immediately after you turn on your Mac.
- Hold these keys down for at least 20 seconds to ensure that your Mac completes the process correctly.
- Release the keys.
