Option 1: Use built-in screen recording on iOS 11 and above
Option 2: Use QuickTime if you use iPhone and Mac
Option 3: Apowersoft Phone Manager for iPhone and Windows PC/Laptop
Option 4: You can also use other devices to record your iPhone screen.
Things To Keep in Mind
Please do not use screen mirroring for your recordings as this gives an impression that real devices are not used while testing.
In Testlio, a video screen recording attachment has to be less than 10 MB and in .mp4 format and with a minimum resolution of 720p. That means you will need to convert and reduce the size of your video files before you attach them to your issue report.
In case you will need help resizing and converting video files, use tips from the Network article.