Swift Object ModelLesson 31Free preview

Swift Extensions

This lesson is part of Swift · All levels

Summary

This lesson reviews Extensions in Swift that allow you to add new functionality to an existing class, struct, enum, or protocol type, even without having access to the original source code. Extensions can add computed properties, new methods, initializers, and make existing types adopt new protocols separately.

Key points

Extensions extend existing types with the keyword 'NameType extension {...}'
Can add computed properties (but not stored properties)
You can add new methods, mutating methods, and convenience initializers.
It is very popular for organizing code and adopting protocol separately (separation of concerns).

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