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Learning Swift by Andrew J Wagner

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Types

The type system in Objective-C is a little bit more disparate than Swift. This is because the structures and enumerations in Objective-C come from C. Only classes and categories come from the Objective-C extension.

Structures

In Swift, structures are very similar to classes, but in Objective-C, they are much more different. Structures in Objective-C are essentially just a way of giving a name to a collection of individual types. They cannot contain methods. Even more restrictive than that, structures can't contain Objective-C types. That leaves us with only the basic possibilities:

struct Cylinder { var radius: Int var height: Int } var c = Cylinder(radius: 10, height: 10) typedef struct { int radius; int height; } Cylinder; Cylinder c; c.radius ...

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