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

Posted by Nate Bird
Nate Bird
7,999 Points

Compiling error caused by incorrect instructions?

I think the instructions for the swift dictionaries is incorrect. It asks to create a constant for the dictionary but that produces a compiler error when you try to change the dictionary (as it should).

Setting the dictionary as a var works fine as was demonstrated in the accompanying video.

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

let ukCurrency = "Pound"

currencies["UK"] = ukCurrency

2 Answers

James Pamplona
James Pamplona
10,015 Points

Assign the value for key "UK" to a constant named ukCurrency.

The question sentence is a little hard to parse. The question is asking you to create a constant called ukCurrency and assign it the value of the key "UK" from the dictionary. Not modify the dictionary with a new value.

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

let ukCurrency = currencies["UK"]

The last line is what it's asking for.

Nate Bird
Nate Bird
7,999 Points

Thank you. That makes sense.

Nate Bird
Nate Bird
7,999 Points
Nate Bird
Nate Bird
7,999 Points

Ah, you are correct. That makes sense. Then it doesn’t matter if the dictionary is a constant or not.

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

let ukCurrency = currencies["UK”]