Notice how it by default selects the “Touch Up Inside” event for you. This is good because it means when the user’s finger moves up from the button (i.e. they tapped it), your method will be called.
You can connect other actions to callback methods too. For example, there’s an action on the text field when the text changes, and you want to get a callback when this happens.
To do this, control-drag from the Text Field right before the @end and also set it to Action. By default it sets the event to Editing Did End – change this to Editing Changed. Name the method titleFieldTextChanged, and click Connect.