1. Open the setting interface, as shown in the figure below.

2. Click the general menu in the above figure to enter the interface below.

3. Click the "iPhone Storage Space" menu to enter the interface shown below.

4. Start "Uninstall Unused Applications" to clear the memory, so as to alleviate the problem of insufficient memory in the mobile phone space.

5. Slide the list to the bottom to see the space occupied by the system. As you can see in the figure, the official version of iOS 1 1.2 takes up 5.38G of memory.