In iOS 11, you can create a screen recording and capture sound on your iPhone, iPad, or iPod touch.
Record your screen
- Add Screen Recording to Control Center. Go to Settings > Control Center > Customize Controls, then tap next to Screen Recording.
- Open Control Center.
- To capture sound while you record, press deeply on and tap Microphone Audio.
- Tap, then wait for the three-second countdown.
- To stop recording, open Control Center and tap . Or tap the red status bar at the top of your screen and tap Stop.
You can find your screen recording in the Photos app.
Apple KB Article: https://support.apple.com/en-us/HT207935
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