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

Posted by Oliver Lebert
Oliver Lebert
241 Points

Can you see what's wrong with this code?

I cannot understand what is wrong with this.

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

3 Answers

Lukas Smith
Lukas Smith
4,026 Points
Lukas Smith
Lukas Smith
4,026 Points

U used LET it is constant so U must change for var currencies = ["US":"Dollar","UK":"Pound","JP":"Yen"] let ukCurrency = currencies.removeValueForKey("UK")

kjvswift93
kjvswift93
13,515 Points
kjvswift93
kjvswift93
13,515 Points

This would work if you had declared the currencies dictionary as a variable, yet since it is a constant whose key's values are immutable types of [String: String], using removeValueForKey attempts to mutate the dictionary and therefore results in a compiler error. What you need to do here is "capture" a value from the dictionary without changing it.

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