Hands-On Design Patterns with Swift

Type aliases

Type aliases are a simple addition to the language; they let you reference simple or complex types by an alias. They support all declarations that you can imagine, from the simplest to the most complex.

The following block contains declarations for aliasing the following:

• A string class into a MyString
• A function declaration into a Block
• A block that takes any argument and returns any value
• A block that takes no argument and returns any value

Let's see the code block; they let you:

typealias MyString = Stringtypealias Block = () -> Voidtypealias TypedBlock<T, U> = (T) -> Utypealias ReturningBlock<U> = () -> U

We could have also defined Block in the function of ReturningBlock:

typealias Block = ReturningBlock<()>

You can also ...