14.9 Swift Dictionary Initialization

A dictionary is a data type designed specifically to hold multiple values in a single unordered collection. Each item in a dictionary consists of a key and an associated value. The data types of the key and value elements type may be specified specifically using type annotation, or left to the compiler to identify using type inference.

A new dictionary may be initialized with a collection of values (referred to as a dictionary literal) at creation time using the following syntax:

var variableName: [key type: value type] = [key 1: value 1, key 2: value2 …. ]

The following code creates a new array assigned to a variable (thereby making it mutable) that is initialized with four key-value pairs in the form of ISBN numbers acting as keys for corresponding book titles:

var bookDict = ["100-432112" : "Wind in the Willows",

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