不少 APP 都有操作演示视频，不知道是怎么将操作过程的屏幕录下来的？
当然绝对不是弄个外接摄像头录制
http://www.airserver.com/，ios设备和PC/MAC在同一局域网下，可air play到PC/MAC，同时可录像。
我们演示产品的时候经常用，投影到大屏幕上
With iOS 8 and OS X Yosemite, you can capture real-time footage of your app directly from your iOS device. Simply connect your device to your Mac using the Lightning connector and it will be automatically available as a video camera. You can capture anything you’re doing on-screen directly to your Mac using QuickTime Player. Edit your captured footage in iMovie or your favorite video editing app and upload it to iTunes Connect for review along with your next app update.
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