Dictionaries
Dictionary literals start with an opening brace { and end with a closing brace }. Keys are separated from values by a colon, and key-value associations are separated by commas.
1. Types
Dictionary types have the form {K: V}, where K is the type of the key, and V is the type of the value. For example, a dictionary with Int keys and Bool values has type {Int: Bool}.
In a dictionary, all keys must have a type that is a subtype of the dictionary's key type (K) and all values must have a type that is a subtype of the dictionary's value type (V).
Declare a constant that has type {Int: Bool},
let integers = {
true: 1,
false: 0
}
2. Access
To get the value for a specific key from a dictionary, the access syntax can be used: The dictionary is followed by an opening square bracket [, the key, and ends with a closing square bracket ].
Declare a constant that has type {Int: Bool},
let integers = {
true: 1,
false: 0
}
integers[true] // is 1
integers[false] // is 0
integers[false] = 9 // is now 9
3. Fields and Functions
Examples of functions of a dictionary
let numbers = {"fortyTwo": 42, "twentyThree": 23}
numbers.length // 2
numbers.insert(key: "fortyTwo", 42)
numbers.remove(key: "fortyTwo") // 42 popped
numbers.values // numbers is now [42, 23]