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Protocols in Swift
Protocols are extremely important in Swift
A protocol allows objects, and provide a concrete implementation of any object that conforms to it. We can think of a protocol as a set of rules and guidelines that an object can conform to
For the examples, read on.
Difficulty: Beginner | Easy | Normal | Challenging
Prerequisites:
- Be able to produce a “Hello, World!” iOS application (guide HERE)
- Use of extensions (guide HERE)
- Some knowledge of Object-oriented programming, specifically overriding (guide HERE)
Terminology
class: An object defined in Swift, using pass by reference semantics
conforms: conformance is if an object adopts a protocol (or inherits it from another class) and contains the functionality specified
enum: A type consisting of a set of named values, called members
extensions: Extensions add new functionality to a class, struct, enum or protocol
inheritance: The mechanism in which one class acquires the property of another class
method: A group of statements that together can perform a function
protocol: A blueprint on methods, properties and requirements to suit a piece of functionality
property: An association of a value with a class, structure or enumeration
struct: An object defined in Swift, using pass by value semantics
The origin of protocols
In natural English a protocol is a say that two parties agree to communicate. A simple example of this is a traditional handshake in England (an alternative is the bow in Japan).
In computing this idea has often been adopted in communications, for example the sending of acknowledgements in the Internet Protocol.
The meaning of protocol in Swift is tightly coupled to this meaning, although it is subtly…
