The iOS devices have built-in encryption between the flash memory and the system's main memory. For this reason, iOS devices can be deleted using Cryptographic Erase. This process deletes the old AES-256 encryption keys and renders all user data on the device cryptographically inaccessible.
In BMDE it is possible to delete iOS devices with Cryptographic Erase, but in addition it is also possible to delete the encrypted memory.
The deletion standards on iOS delete the device as follows: