The docs for UIWritingToolsCoordinator's isWritingToolsAvailable have been updated in the 27 SDK.
Previously, the docs stated:
Writing Tools support might be unavailable because of device constraints or because the system isn’t ready to process Writing Tools requests.
They now say:
Writing Tools support might be unavailable because of device constraints.
Is this a change in behaviour between SDK 26 and 27, or have the docs just been updated to more accurately describe the behaviour?
The wording in the documentation has been changed to more accurately describe the expected return value of the method. The method would return YES even if the user has not enabled the Apple Intelligence features or the supporting files are downloading. In other words, the only reason that this method returns NO is that the hardware does not support Writing Tools or Siri AI is enabled.
This means you should use this method to determine the "entry point" of your Writing Tools feature. For example, this method should be used to determine the visibility of the Writing Tools button on the toolbar. In that case, the button is shown if the hardware is capable. When the user taps on it and when Writing Tools is not enabled or ready, the app should punch out to Settings. When the device has Siri AI, the button is hidden as Siri AI offers broader functionality.
