The process to perform a software update involves multiple steps—from the detection of an available update, to downloading and preparing the update, to the actual installation.
After an update becomes available for iPhone, iPad, or Mac, it’s detected in one of the following methods:
If the device is using the default configuration and the requirements for a software updates are met, users can navigate to Settings (on iOS and iPadOS) or System Settings (on macOS) to download, prepare, and install the update at a time convenient for them.
When connected wirelessly, iPhone and iPad devices use an over-the-air (OTA) update method that downloads only the components required to complete an update. This update improves network efficiency and enables faster downloads.
iOS and iPadOS software updates are made available in two phases, which determine how they can be downloaded.
iPhone and iPad can download and prepare software updates when connected using Wi-Fi and when connected using cellular:
Similar to updates for iOS and iPadOS, updates for macOS are incremental updates using the OTA update method, which downloads only the components necessary to update the specific device. Incremental updates require a sealed system volume.
After an update has been downloaded and prepared, a notification is shown to the user and a red icon appears over the Settings app (on iOS and iPadOS) or the System Settings app (on macOS). If automatic downloads are turned off, the notification and badge are shown when the update is detected.
iPhone and iPad
If a passcode has been configured on the device, users are prompted for it to authorize the update.
Mac
In macOS 12.3 or later, any local user can authorize incremental software updates. Before macOS 12.3 , local administrators are required to perform software upgrades. On a Mac with Apple silicon, users must be a volume owner to perform an update.
The Universal Mac Assistant (UMA) is a full installer of macOS and can be used on any supported Mac. The UMA is available using the softwareupdate command-line tool and requires authorization by a local administrator to be installed.
Automatic installation of software updates (not upgrades) and Rapid Security Responses
After the preparation is complete and users have automatic software updates or Rapid Security Responses turned on, the device uses on-device machine learning to determine a suitable time to install them.
To authorize the update, devices try to use the passcode or password from unlock to perform an automatic update, but may prompt the user instead.
In addition to other software update requirements, Mac computers must have no apps or processes running which block a restart. Mac laptops can have their lid closed.