How to record iPhone/iPad screen in Windows
According to 9to5Mac, iOS 11 includes a dedicated Screen Recorder which can be used without connecting to a Mac.


  Enabling screen recording on iOS 11
  
  
  Launch Settings → Control Center → Customize Controls.
  Scroll down in the list and add Screen Recording
  Close Settings
  
  
  
  
  
  Swipe-up from the bottom of the display to reveal Control Center
  Tap Screen Recording button to immediately begin recording (or 3D Touch to bring up menu)
  
  
  



Source: 9toMac - How to enable screen recording on iOS 11 without a computer