IOS Screen Savers

Hello there! Lately I have been trying to create my own screen savers on IOS system but haven't been able too. From my point of view it should just be a video clip on repeat that you drop in the screen saver file but that doesn't seem to be the case on IOS. If you have any information on exactly what a IOS screen saver is and how to create one that would be fantastic! Thanks for your time.