iOS Design Patterns

A design pattern is a template for a design that solves a general, recurring problem in a particular context. It is a tool of abstraction that is useful in fields like architecture and engineering as well as software development.

• a. Abstract Factory Pattern
• b. Adaptor Pattern
• c. Object Modeling Pattern
• d. Chain of Responsibility Pattern
• e. Command Pattern
• f. Composite Pattern
• g. Decorator Pattern
• h. Facade Pattern
• i. Iterator Pattern
• j. Mediator Pattern
• k. Memento Pattern
• l. Model-View-Controller Pattern
• m. Observer Pattern
• n. Proxy Pattern
• o. Receptionist Pattern
• p. Singleton Pattern
• q. Template Method Pattern

Design patterns are separated into three categories: creational, structural, and behavioral.

• Creational patterns are design patterns specifically used for dealing with the creation of objects. The abstract factory and singleton are considered creational patterns.
• Structural patterns are used to define structures of objects. The adaptor, composite, decorator, and proxy patterns are types of structural design patterns.
• Behavioral patterns identify communication between objects. The chain of responsibility, command, iterator, memento, observer, and template method are examples of behavioral design patterns.

The Model-View-Controller (MVC) design pattern is considered the cornerstone design pattern for iOS app development. The MVC design pattern consists of three parts: model, view, and controller. The model contains data, information, logic, or objects considered part of the business layer of an iOS app. The view contains all of the user information components-such as text areas, buttons, and sliders considered the presentation layer of an iOS app. The controller is the liaison, or communication layer, of an iOS app

Similarly Delegation, and Target-action design patterns. The delegation pattern is based on the concept of one object acting on behalf of another, while target-action is a design pattern where an object stores information that will be sent to a specific object when a certain event happens.

These three design patterns are considered fundamental building blocks for iOS app development.