1. Open any mobile browser (Safari/UC browser is ok).

2. Enter ipsw.me in the address bar;

3. Select a device in the opened webpage, and select the device model you want to view;

4. After selecting the device, click to select the iOS version, and the firmware version will appear. Green indicates that the verification is not closed, and red indicates that it is closed.

In addition, on the PC, you can also check the website through the iOS firmware (click to enter) to find out whether the firmware verification such as iOS 9.0 is turned off.

In fact, after the update of iOS 9.0.2 was pushed yesterday morning, Apple officially announced that code signing verification of iOS 8.4. 1 and iOS 9.0 had been closed, and users upgrading the new system would not be downgraded. Foreign media said that Apple's move is to ensure the smoothness and stability of the system.