Target/Action: Design pattern known for handling to controls (UIButton, UITextField etc) events. Target Action In the above diagram UIViewController (target) is responsible for action of UIButton (control). This design pattern enables to write the custom logic of controls in any object (UIViewController) without sub classing the control (UIButton) object. So if you connect a button to an outlet in storyboard it depicts the target/action paradigm. The action is defined by the name of a selector. The target can either be a concrete object or it can be NULL We can take the example of this pattern as if we press (Action) a electricity switch then target (Fan) will start rotating. Code : In programming we are using this pattern when we use the following method for any controls: addTarget:action:forControlEvents: When we add any action through xib or storyboard then also we are using action target design pattern. So ...