hashable_dictionary_example.swift

// instantiate a dictionary
var personalInfo = ["firstName": "John", "address": "1100 Main St."]
// data retrieval
let firstName = personalInfo["firstName"]
let middleName = personalInfo["middleName"]
// data insertion
personalInfo["lastName"] = "Smith"
personalInfo["firstName"] = "Mike"
// data deletion
let deletedAddress = personalInfo.removeValue(forKey: "address")
let deletedMiddleName = personalInfo.removeValue(forKey: "middleName")