1. To start recording the IOS 8 device screen, you need to first run QuickTime Player application on the MAC running OS X Yosemite. We can find it inside the application.
2, then click "File" > new movie recording in the upper right corner (Movie recording).
3. After clicking, QuickTime Player will open and try to record you through the FaceTime camera. Next you need to move to the Drop-down arrow next to the Recording button and select your IOS device from the source list, as shown below.
You can choose to import video input and audio. You can import video from iOS or Mac, or you can import audio from iOS or Mac.
4, recording finished, remember to store good video files, recorded a good file format for MOV format, if you need to upload to the network may need to do video format conversion.
This screen feature is a useful addition to OS X, and is also suitable for people who need to record video games or tutorial videos. Once the device running the iOS 8 system is plugged into a Mac running OS X Yosemite via a USB cable, your iOS 8 device will appear in the camera source list. This allows you to easily switch to the ability to record the IOS 8 device screen, which is very handy and fast.