Enumeration CFNotification Suspension Behavior
Suspension flags that indicate how distributed notifications should be handled when the receiving application is in the background.
iOS 2.0+ macOS 10.0+ tvOS 9.0+ watchOS 2.0+ Declaration enum CFNotificationSuspensionBehavior :
CFIndex Topics Constants case drop
The server will not queue any notifications of the specified name and object while the receiving application is in the background.
The server will only queue the last notification of the specified name and object; earlier notifications are dropped.
The server will hold all matching notifications until the queue has been filled (queue size determined by the server) at which point the server may flush queued notifications.
case deliver Immediately
The server will deliver notifications of the specified name and object whether or not the application is in the background. When a notification with this suspension behavior is matched, it has the effect of first flushing any queued notifications.