Dictionary Lookup - Swift Programming

Dictionaries map keys to values so code can look up a value by name.

Read by key

dictionary_lookup.swift

let city = 
let temperatures = ["Austin": 72, "Denver": 55, "Seattle": 63]
let current = temperatures[city]!
let warmEnough = current >= 65

print("city=\(city)")
print("temperature=\(current)")
print("warmEnough=\(warmEnough)")

let city = 
let temperatures = ["Austin": 72, "Denver": 55, "Seattle": 63]
let current = temperatures[city]!
let warmEnough = current >= 65

print("city=\(city)")
print("temperature=\(current)")
print("warmEnough=\(warmEnough)")

let city = 
let temperatures = ["Austin": 72, "Denver": 55, "Seattle": 63]
let current = temperatures[city]!
let warmEnough = current >= 65

print("city=\(city)")
print("temperature=\(current)")
print("warmEnough=\(warmEnough)")

dictionaries A dictionary lookup uses a key. When the key is known to exist, unwrapping the result gives the stored value for later calculations.