Swift version: 5.0
A dictionary is a collection of values stored at named positions. Whereas you would access values in an array using
myArray, with a dictionary you use named positions such as
myDict["Scotland"]. You don't even need to use strings for the positions – you can use another object if you choose, such as dates.
These named positions are called "keys", so dictionaries represent what's known as a key-value pair: each key has exactly one value, and each can appear only once in a dictionary.
Available from iOS 7.0 – learn more in my book
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.