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iOS Swift Basics (retired) Collections What is a Dictionary?

Posted by joshuawalliy
joshuawalliy
1,131 Points

Why isn't this working.

let currencies = [ "US" : "Dollar", "UK" : "Pound", "JP" : "Yen"] let ukCurrency ;["UK"]

The system says its wrong why?

dictionaries.swift 
let currencies = [ "US" : "Dollar", "UK" : "Pound", "JP" : "Yen"]
let ukCurrency ;["UK"]

2 Answers

Ricardo Hill-Henry
Ricardo Hill-Henry
38,442 Points
Ricardo Hill-Henry
Ricardo Hill-Henry
38,442 Points

To call a dictionary, you use the variable or constant name you assigned it, followed by square brackets, and the key for the value you're attempting to retrieve. For example:

// Declaring myDictionary
var myDictionary = ["key1" : "value1", "key2" : "value2", "key2" : "value2"];

// Retrieving a value from myDictionary
myDictionary["key1"]; // returns "value2"
Kristian Egebæk-Carlsen
Kristian Egebæk-Carlsen
9,189 Points
Kristian Egebæk-Carlsen
Kristian Egebæk-Carlsen
9,189 Points

You are trying to create a constant called ukCurrency, but when you assign a constant you need the '=' to let to program know what the constant should be. Then you need to acces your dictionary to find the value for "UK". Therefore the constant declaration should be let ukCurrency = currencies["UK"]. This will create a new constant ukCurrency and assign the value of currencies["UK"] which is "Pound"