An outlet is a property that is annotated with the symbol IBOutlet and whose value you can set graphically in a nib file or a storyboard. You declare an outlet in the interface of a class, and you make a connection between the outlet and another object in the nib file or storyboard. When the file is loaded, the connection is established.
You define an outlet as a property with the type qualifier of
@property (nonatomic, weak) IBOutlet UITextField *nameField;
IBOutlet is used only by Xcode, to determine when a property is an outlet; it has no actual value.
Through an outlet, an object in your code can obtain a reference to an object defined in a nib file or storyboard and then loaded from that file. The object containing an outlet is often a custom controller object such as a view controller. You frequently define outlets so that you can send messages to view objects of the UIKit framework (in iOS) and the AppKit framework (in OS X).