Editing Apple (section)

=== Operating system downgrades ===
It is not possible to upgrade or downgrade an iPhone, iPad, Apple TV, etc. to an Operating System (OS) version other than the absolute latest. On Macs with T2 chip or Apple Silicon, the user can select from three modes of secure boot:<ref>https://support.apple.com/102522</ref>

*No security: Allow any OS to run (same as turning off secure boot on a PC).
*Medium security: Allow any OS that is signed with a secure boot certificate (default, same as turning on secure boot on a PC).
*Full security: Only allow the latest version of macOS, do not allow any other OS.

iOS devices only support full security mode. The device checks for a cryptographic "[https://theapplewiki.com/wiki/APTicket ticket]," which are tied to the OS version and CPU serial number. These are provided by a server, which only provides them for the latest version (with very specific exceptions). The device refuses to boot if the ticket does not match. [https://theapplewiki.com/wiki/Firmware_downgrading Workarounds] exist, but with major caveats that are not viable for most users.<ref>https://en.wikipedia.org/wiki/SHSH_blob</ref>

====Class Action====
Apple was the defendant of a class-action lawsuit with claims dating back to 2017 where users noticed their phones were being artificially slowed down. Apple agreed to settle the lawsuit for up to 500 million.<ref>CNET Article: https://www.cnet.com/tech/mobile/apple-starts-sending-out-iphone-batterygate-settlement-payments-what-to-know/</ref> Apple claimed that this change was to benefit users who have old failing batteries, and that it wasn't for planned obsolescence. They later published software updates and an article explaining how users can opt out of this new "performance management" mode.<ref>Apple battery performance management https://support.apple.com/en-us/101575</ref>


Once a new OS version is installed, there is no opportunity to go back. This also restricts the user's choice to jailbreak the device, as the latest version naturally has patches for the latest jailbreak exploits. App developers also require access to earlier iOS versions to test that their app works correctly. The alternative, Xcode's iOS Simulator, is not a complete replacement for real hardware, as it does not have all features of a physical device.<ref>https://contextqa.com/test-on-ios-emulators-simulators/</ref> Instead, app developers are forced to purchase several test devices, and remember to ''never'' allow them to update.