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iOS

Posted by Kirk Lewis
Kirk Lewis
1,486 Points

Is this Key value question a bug? Will not let me move forward.

Question: Let's create a dictionary that contains the currencies of the various countries along with their country codes. The country code will be the key and the currency the value. Using the following key-value pairs: US : Dollar, UK : Pound, JP : Yen assign them to a constant named currencies.

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

SAYS IT'S CORRECT AND MOVES FORWARD TO THIS: Question: Assign the value for key "UK" to a constant named ukCurrency.

MY ANSWER: let ukCurrency = currencies.removeValueForKey("UK")

Keeps giving me an error... All types of errors... depends on how I keep changing the code around.

In XCode I use this and I get no Errors (Notice the var instead of let): var currencies = ["US": "Dollar", "UK": "Pound", "JP": "Yen"] let ukCurrency = currencies.removeValueForKey("UK")

So what is the deal here? I think that this constant erroring and forcing me to try different things is counter-productive to me actually learning. Is this an error in this program/quiz?

Thank you

3 Answers

Dennis Parussini
.a{fill-rule:evenodd;}techdegree seal-36
Dennis Parussini
Treehouse Project Reviewer

Hey Kirk,

the answer is actually pretty simple:

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

You assign the value of "currencies" to a new constant. What you did is remove a value from the dictionary. In real code this is also valid, but the question was to assign a given value to a new constant.

Hope I could help you with that. :-)

Damien Watson
Damien Watson
27,419 Points
Damien Watson
Damien Watson
27,419 Points

Hey Kirk,

Is the second question basically stating to now modify the existing code to use a constant for 'UK'. Because currencies is defined as a constant, you can't modify it, so your code should be something like:

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

Sorry if this is off, I haven't started the Swift course yet. :)

Kirk Lewis
Kirk Lewis
1,486 Points
Kirk Lewis
Kirk Lewis
1,486 Points

Yes that was helpful. I can't believe I didn't try that! Actually, I tried currencies ("UK")

Maybe I was too sleepy! but anyway, thank you mucho!

Dennis Parussini
.a{fill-rule:evenodd;}techdegree seal-36
Dennis Parussini
Treehouse Project Reviewer

You're very welcome.

Actually currencies() is initializer syntax, that means that you would initialize a new instance of currencies (if currencies was a class ;-)). Remember, if you want to retrieve a value from an array or dictionary always use [] after the name of the array or dict.