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Mastering Swift 4 - Fourth Edition by Jon Hoffman

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Generic types

We have already had a general introduction to how generic types work when we looked at Swift arrays and dictionaries. A generic type is a class, structure, or enumeration that can work with any type, just like the way Swift arrays and dictionaries work. As we recall, Swift arrays and dictionaries are written so that they can contain any type. The catch is that we cannot mix and match different types within an array or dictionary. When we create an instance of our generic type, we define the type that the instance will work with. After we define that type, we cannot change the type for that instance.

To demonstrate how to create a generic type, let's create a simple List class. This class will use a Swift array as the backend ...

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