You must be in Interface Builder, have created a button (see HowToCreateAButton), have a class instantiated (see HowToCreateAClassInInterfaceBuilder and HowToInstantiateAClassInInterfaceBuilder), and have one or more action methods defined in your class (see HowToDefineAnActionMethod) in order to link your button to an action method.
Assuming you have these, control drag from the button to the instantiated class. (Control dragging involves selecting the button, holding down control, dragging the line to the class and releasing the mouse button. It may be complex for the first few times). In the info panel select the action method you want then hit the “connect” button. All done.
Now if you test the interface (see HowToTestTheInterface), you will see that pressing the button performs your action method. Pretty cool, huh?
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