You know how you can press the home and side button simultaneously to take a snapshot of the screen, well, can you "snapshoot" a video of activity on your iPhone, like, a segment of a YouTube video (sometimes, something like t=1m45s on the end of a YouTube link doesn't get pushed to that time when clicked on certain devices) or "snapshoot" a process. That is, if I wanted to demonstrate steps quickly and easily I could press some buttons simultaneously and start recording, then do some things on my iPhone, then press some buttons and then it stops, and now I have a video of that activity in my videos. Is that a thing?
With iOS 11, you can use Screen Recording built in to the OS.
- Go to Settings → Control Center and add Screen Recording.
- When you're ready to record, swipe from the bottom of the screen to show Control Center, then tap the Screen Recording button. 3D Touch the icon for additional options such as recording the microphone.
- Continue using your device and your display will be recorded.
- To stop the recording, tap the Screen Recording button once more. The video is saved to your camera roll.
If your device is jailbroken, you can use Display Recorder which performs similar functionality for older versions of iOS.
Less convenient than the onboard recording in iOS 11, but in iOS 10 you can record the screen with QuickTime on a Mac.
- Connect your iPhone to a Mac using a Lightning cable.
- Open QuickTime Player on your Mac
- Select "New Movie Recording" from the File menu.
- Click the downward-pointing chevron beside the record button to change the Camera and Microphone sources to your iPhone. You can also change the quality of the recording from the same menu.
- Click the record button in QuickTime Player to start recording.
- Perform whatever actions you want on your iPhone.
- Click the stop button in QuickTime Player to stop recording.