In Swift, convenience initializers offer a simpler, more streamlined way to create instances of a class. They are secondary, supporting initializers that call the class's designated initializer. This allows for initializing an object with fewer or default parameters. For instance, in a FantasyCharacter class, while the designated initializer requires a name, role, and hit points, a convenience initializer can allow creation of a character with just a name, automatically assigning a default role and hit points. This simplifies object creation, especially when full customization isn't needed, making your code more flexible and user-friendly.