The main difference is that iOS controls can have several actions for different events, but there is only one main action for managing Mac OS X (in some cases there are others that can be configured programmatically).
When you right-click on a button in Mac nib, it’s performClick:located in the “Received Actions” section; this is not an event. The only entry in the Sent Actions section is the selector, which is the only thing you can connect to an action on another object.
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