在推送iOS 9.0.2更新之后，苹果宣布，已经关闭iOS 8.4.1、iOS 9.0代码签名验证，升级新版系统的用户将无法降级。外媒表示，苹果此举为了保Music和iCloud Music音乐库等...
after pushing IOS 9.0.2 update, Apple announced, has closed IOS 8.4.1, IOS 9.0 code signature verification, upgraded version of the system users will not be able to downgrade. Foreign media said Apple's move to protect the iCloud and Music Music music library, etc....
