Dictionary Literal

We can also create dictionaries which are initialised with elements. 
In a dictionary, an element refers to a single key-value pair.

To create a populated dictionary, we will use dictionary literal syntax.

SYNTAX:
var dictionaryName: [KeyType: ValueType] = [
  Key1: Value1,
  Key2: Value2,
  Key3: Value3
]

// There is a type annotation for both the key and the value.
// Each key is unique.
// The keys and values must belong to their specified type.
// The key and the value are separated by a colon :.
// All of the elements are contained within brackets [].
// Each key-value pair is separated by a comma ,

EXAMPLE:
Let’s create a dictionary called fruitStand that stores information about fruit stock

var fruitStand: [String: Int] = [
  "Apples": 12,
  "Bananas": 20
]

// The keys are type String and the values are type Int.
// There are two key-value pairs in our dictionary.
// One pair has a key of "Apples" with a value of 12.
// The other pair has a key of "Bananas" and a value of 20.

OUTPUT:
Using print() to output value: 

["Bananas": 20, "Apples": 12]

Dictionaries are unordered - when we use print() to output a dictionary, the order of the elements may not appear in the order they were added in.

EXAMPLE:
var roleModels: [String: String] = [
  "Mr. Rogers": "Fred McFeely Rogers",
  "The Crocodile Hunter": "Stephen Robert Irwin",
  "Bill Nye the Science Guy": "William Sanford Nye"
]

print(roleModels)

OUTPUT:
["Bill Nye the Science Guy": "William Sanford Nye", "The Crocodile Hunter": "Stephen Robert Irwin", "Mr. Rogers": "Fred McFeely Rogers"]

// Output changes every time we run the code as dictionary is unordered.