Lesson 16 - Extensions and their use in Swift
In the previous lesson, Enums and custom errors in Swift, we learned how to use enumerated types and define custom error states in Swift.
Swift offers us the possibility to add functionality to existing data types,
split a class implementation into multiple files or code blocks, and much more.
That's what a powerful concept called extensions does. In
today's tutorial, we'll show you how to add new methods to existing classes or
structs (such as an ordinary
Int), separate a protocol
implementation and other tricks.
Extending existing types
This usage of
extension is useful when we can’t edit some
existing code. It can be either a part of the language like
String, etc. or, for example, a downloaded library. Perhaps the
most useful feature is to add new methods to classes that aren't even ours and
we have no access to them or don't want to interfere with them.
For example, consider we
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