11 Protocols and Delegates
WHAT YOU WILL LEARN IN THIS CHAPTER:
- What a protocol is
- How to define and use a protocol
- How to conform to a protocol
- How to declare optional methods in a protocol
- How to conform to multiple protocols
- How to specify property requirements in a protocol
- How to specify initializer requirements in a protocol
- What a delegate is
- How to create and use a delegate
- How protocols and delegates are used in real-life apps
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The use of protocols and delegates reflects one of the most important design patterns in Swift programming. In Chapters 8 and 9 you have seen how classes and inheritance work; and in this chapter, you will learn both how to use protocols to enforce the content of a class and how delegates help to create events and event handlers.
UNDERSTANDING PROTOCOLS
A protocol is a blueprint of methods and properties. It describes what a class should have, and it does not provide any implementation. A class that conforms to a protocol needs to provide the implementation as dictated by the protocol. A protocol can be implemented by a class, a structure, or an enumeration.
Defining and Using a Protocol
To define a protocol, use the protocol keyword, followed by the name of the protocol:
protocol ProtocolName { func method1() ...Get Beginning Swift Programming now with the O’Reilly learning platform.
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