Adds an observer to a notification center.
cocoa
add-observer target selector &key name object center
| target⇩ |
A pointer to an Objective-C foreign object. |
| selector⇩ |
A selector of type sel. |
| name⇩ |
A string or nil. |
| object⇩ |
A pointer to an Objective-C foreign object or nil. |
| center⇩ |
A notification center. |
The function add-observer calls the Objective-C instance method "addObserver:selector:name:object:" of center to add target as an observer for selector with the given name and object, which both default to nil.
If center is omitted then it defaults to the default notification center.
LispWorks Objective-C and Cocoa Interface User Guide and Reference Manual - 01 Dec 2021 19:38:33