Users who like Apple mobile phones are familiar with and accustomed to iOS, and may not be uncomfortable even after returning from Android. Even old models such as iPhone 6s and iPhone 7 can be upgraded to the latest iOS 14. After a period of time, this is good-looking and convenient. The previous official version has rich, stable and smooth functions, but recently the iPhone 12 green screen door and battery door have problems. Some people say it is related to the iOS mobile phone system. It feels that Apple has been optimizing this point recently.