The data in the keychain item can be accessed only while the device is unlocked by the user.
- iOS 4.0+
- macOS 10.9+
- tvOS 9.0+
- watchOS 2.0+
This is recommended for items that need to be accessible only while the application is in the foreground. Items with this attribute do not migrate to a new device. Thus, after restoring from a backup of a different device, these items will not be present.