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What is a dictionary? - free Swift 4.2 example code and tips

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What is a dictionary?

Paul Hudson       @twostraws

A dictionary is a collection of values stored at named positions. Whereas you would access values in an array using myArray[5], with a dictionary you use named positions such as myDict["Paul"] or 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

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