Apple: Difference between revisions

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===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 most recent. 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>

It is not possible to upgrade or downgrade an iPhone, iPad, Apple TV, etc. to an Operating System (OS) version other than the most recent. On Macs with T2 chip or Apple Silicon, the user can select from three modes of secure boot:<ref>{{Cite web |title=About Startup Security Utility on a Mac with the Apple T2 Security Chip |url=https://support.apple.com/en-us/102522 |url-status=live |archive-url=https://web.archive.org/web/20250607083624/https://support.apple.com/en-us/102522 |archive-date=7 Jun 2025 |access-date=22 Jun 2025 |website=Apple}}</ref>

*No security: Allow any OS to run (same as turning off secure boot on a PC).

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*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>~~

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, see the technical details on [[wikipedia:SHSH_blob|SHSH blobs]].

===Class action lawsuit===

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 USD.<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>

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 USD.<ref>{{Cite web |last=Cooper |first=Gael |date=9 Jan 2024 |title=Apple Starts Sending Out iPhone 'Batterygate' Settlement Payments. What to Know |url=https://www.cnet.com/tech/mobile/apple-starts-sending-out-iphone-batterygate-settlement-payments-what-to-know/ |url-status=live |archive-url=https://web.archive.org/web/20250321051703/https://www.cnet.com/tech/mobile/apple-starts-sending-out-iphone-batterygate-settlement-payments-what-to-know/ |archive-date=21 Mar 2025 |access-date=22 Jun 2025 |website=CNET}}</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>{{Cite web |title=iPhone battery and performance |url=https://support.apple.com/en-us/101575 |url-status=live |archive-url=https://web.archive.org/web/20250618231138/https://support.apple.com/en-us/101575 |archive-date=18 Jun 2025 |access-date=22 Jun 2025 |website=Apple}}</ref>

Once a new OS version is installed, there is no opportunity to go back. This also restricts the user's choice to {{Wplink|iOS jailbreaking|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.

Once a new OS version is installed, there is no opportunity to go back. This also restricts the user's choice to {{Wplink|iOS jailbreaking|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>{{Cite web |last=Vajpai |first=Shreeti |date=24 Jun 2024 |title=iOS Emulators / Simulators vs Real iOS Devices |url=https://contextqa.com/test-on-ios-emulators-simulators/ |url-status=dead |archive-url=https://web.archive.org/web/20250519081214/https://contextqa.com/test-on-ios-emulators-simulators/ |archive-date=19 May 2025 |access-date=22 Jun 2025 |website=ContextQA}}</ref> Instead, app developers are forced to purchase several test devices, and remember to ''never'' allow them to update.

===Parts availability===

@@ Line 41: / Line 41: @@
 ===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 most recent. 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>
+It is not possible to upgrade or downgrade an iPhone, iPad, Apple TV, etc. to an Operating System (OS) version other than the most recent. On Macs with T2 chip or Apple Silicon, the user can select from three modes of secure boot:<ref>{{Cite web |title=About Startup Security Utility on a Mac with the Apple T2 Security Chip |url=https://support.apple.com/en-us/102522 |url-status=live |archive-url=https://web.archive.org/web/20250607083624/https://support.apple.com/en-us/102522 |archive-date=7 Jun 2025 |access-date=22 Jun 2025 |website=Apple}}</ref>
 *No security: Allow any OS to run (same as turning off secure boot on a PC).
@@ Line 47: / Line 47: @@
 *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>
+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, see the technical details on [[wikipedia:SHSH_blob|SHSH blobs]].
 ===Class action lawsuit===
-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 USD.<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>
+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 USD.<ref>{{Cite web |last=Cooper |first=Gael |date=9 Jan 2024 |title=Apple Starts Sending Out iPhone 'Batterygate' Settlement Payments. What to Know |url=https://www.cnet.com/tech/mobile/apple-starts-sending-out-iphone-batterygate-settlement-payments-what-to-know/ |url-status=live |archive-url=https://web.archive.org/web/20250321051703/https://www.cnet.com/tech/mobile/apple-starts-sending-out-iphone-batterygate-settlement-payments-what-to-know/ |archive-date=21 Mar 2025 |access-date=22 Jun 2025 |website=CNET}}</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>{{Cite web |title=iPhone battery and performance |url=https://support.apple.com/en-us/101575 |url-status=live |archive-url=https://web.archive.org/web/20250618231138/https://support.apple.com/en-us/101575 |archive-date=18 Jun 2025 |access-date=22 Jun 2025 |website=Apple}}</ref>
-Once a new OS version is installed, there is no opportunity to go back. This also restricts the user's choice to {{Wplink|iOS jailbreaking|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.
+Once a new OS version is installed, there is no opportunity to go back. This also restricts the user's choice to {{Wplink|iOS jailbreaking|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>{{Cite web |last=Vajpai |first=Shreeti |date=24 Jun 2024 |title=iOS Emulators / Simulators vs Real iOS Devices |url=https://contextqa.com/test-on-ios-emulators-simulators/ |url-status=dead |archive-url=https://web.archive.org/web/20250519081214/https://contextqa.com/test-on-ios-emulators-simulators/ |archive-date=19 May 2025 |access-date=22 Jun 2025 |website=ContextQA}}</ref> Instead, app developers are forced to purchase several test devices, and remember to ''never'' allow them to update.
 ===Parts availability===