How to use typealias to make it easier to use complex types

Paul Hudson    February 13th 2018    @twostraws

Although it’s generally a good idea to use structs or classes for defining your types, sometimes you’ll find yourself using tuples. If this happens to you, it’s quite tedious having to type the full definition of your tuple whenever you want to use it, so the typealias lets you create a specific name for it:

typealias Name = (first: String, last: String)

Type aliases are also useful when you might want to change the underlying type used for data. For example, you might store a value as a Float today, but you want to leave open the option to switch to a Double later on. In this situation, you’d use typealias like this:

typealias MyValue = Float

You can then go ahead and use MyValue everywhere in your code, and if you ever choose to change to Double you can just change the type alias and all your code will update.

Available from iOS 8.0 – learn more in my book Pro Swift

Did this solution work for you? Please pass it on!

Tweet

Other people are reading…

• What’s the difference between == and ===?
• What is a singleton?
• What is Automatic Reference Counting (ARC)?
• How to safely use reference types inside value types with isKnownUniquelyReferenced()
• What does an exclamation mark mean?

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.