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# addObserver(_:selector:name:object:suspensionBehavior:)

Adds an entry to the receiver’s dispatch table with a specific observer and suspended-notifications behavior, and optional notification name and sender.

```
func addObserver(_ observer: Any, selector: Selector, name: NSNotification.Name?, object: String?, suspensionBehavior: DistributedNotificationCenter.SuspensionBehavior)
```

## Parameters

`observer`

Object registering as an observer. Must not be `nil`.

`selector`

Selector that specifies the message the receiver sends `notificationObserver` to notify it of the notification posting. Must not be `0`.

`name`

The name of the notification for which to register the observer; that is, only notifications with this name are delivered to the observer. When `nil`, the notification center doesn’t use a notification’s name to decide whether to deliver it to the observer.

`object`

The object whose notifications the observer wants to receive; that is, only notifications sent by this sender are delivered to the observer. When `nil`, the notification center doesn’t use a notification’s sender to decide whether to deliver it to the observer.

`suspensionBehavior`

Notification posting behavior when notification delivery is suspended.

## Discussion

The receiver does not retain `notificationObserver`. Therefore, you should always send `NotificationCenter/removeObserver(_:)` or [`removeObserver(_:name:object:)`](/documentation/Foundation/DistributedNotificationCenter/removeObserver(_:name:object:)) to the receiver before releasing `notificationObserver`.

## See Also

[`postNotificationName(_:object:userInfo:deliverImmediately:)`](/documentation/Foundation/DistributedNotificationCenter/postNotificationName(_:object:userInfo:deliverImmediately:))

Creates a notification with information and an immediate-delivery specifier, and posts it to the receiver.


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