Swift Functional Programming - Second Edition

Collections

Swift provides typed collections such as array, dictionaries, and sets. In Swift, unlike Objective-C, all elements in a collection will have the same type, and we will not be able to change the type of a collection after defining it.

We can define collections as immutable with let and mutable with var, as shown in the following example:

// Arrays and Dictionaries var cheeses = ["Brie", "Tete de Moine", "Cambozola", "Camembert"] cheeses[2] = "Roquefort" var cheeseWinePairs = [     "Brie":"Chardonnay",     "Camembert":"Champagne",     "Gruyere":"Sauvignon Blanc" ] cheeseWinePairs ["Cheddar"] = "Cabarnet Sauvignon" // To create an empty array or dictionary let emptyArray = [String]() let emptyDictionary = Dictionary<String, Float>() cheeses ...