Swift is a powerful and intuitive programming language that allows developers to write software that is incredibly fast and safe by design. Two of the key features of Swift are Extensions and Protocols. This article will provide a comprehensive understanding of these two concepts.
Extensions in Swift add new functionality to an existing class, structure, enumeration, or protocol type. This includes the ability to extend types for which you do not have access to the original source code.
Extensions can add computed instance properties and computed type properties to existing types. Computed properties are properties that do not actually store a value. Instead, they provide a getter and an optional setter to retrieve and set other properties and values indirectly.
Extensions can add new instance methods and type methods to existing types. This enables you to add new functionality to the types for which you do not have access to the original source code.
Extensions can add new initializers to existing types. This allows you to extend other types to accept your own custom types as initializer parameters.
Extensions can add new subscripts to an existing type. Subscripts enable you to access information from a sequence, collection, or list in classes, structures, and enumerations without using a method.
In Swift, a protocol defines a blueprint of methods, properties, and other requirements that suit a particular task or piece of functionality.
The syntax to define protocols is very similar to that of classes, structures, and enumerations.
A protocol can require any conforming type to provide an instance property or type property with a particular name and type. The protocol also specifies whether each property must be gettable or gettable and settable.
Protocols can require specific instance methods and type methods to be implemented by conforming types.
A protocol can inherit one or more other protocols and can add further requirements on top of the requirements it inherits.
You can limit protocol adoption to class types (and not structures or enumerations) by adding the AnyObject or class protocol to a protocol’s inheritance list.
Multiple protocols can be combined together. A protocol composed of multiple, combined protocols is called a protocol composition.
You can check for protocol conformance using the is and as operators described in Type Casting.
By understanding and implementing Extensions and Protocols in Swift, you can write more flexible and reusable code. They are powerful tools that can help you design and structure your code in a clean and efficient manner.