Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

iOS Swift Collections and Control Flow Control Flow With Conditional Statements Working With Switch Statements

Maxwell Catmur
Maxwell Catmur
7,355 Points

how do I append switch statements inside of for loops to arrays when dealing with capital cities?

Please can someone help me with this code challenge? Here is the question:

In the editor we have a dictionary that contains a three letter country code as a key and that country's capital city as the associated value.

We also have three empty arrays, europeanCapitals, asianCapitals, and otherCapitals. The goal is to iterate through the dictionary and end up with just the names of the capital cities in the relevant array.

For example, after you execute the code you write, europeanCapitals will have the values ["Vaduz", "Brussels", "Sofia"] (not necessarily in that order).

To do this you're going to use a switch statement and switch on the key. For cases where the key is a European country, append the value (not the key!) to the europeanCapitals array. For keys that are Asian countries, append the value to asianCapitals and finally for the default case, append the values to otherCapitals.

The code is below: Please can you let me know where I went wrong? Thanks

operators.swift
var europeanCapitals: [String] = []
var asianCapitals: [String] = []
var otherCapitals: [String] = []

let world = [
  "BEL": "Brussels", 
  "LIE": "Vaduz", 
  "BGR": "Sofia", 
  "USA": "Washington D.C.", 
  "MEX": "Mexico City", 
  "BRA": "Brasilia", 
  "IND": "New Delhi", 
  "VNM": "Hanoi"]

for (key, value) in world {
    // Enter your code below
    switch (key, value) {
        case "BEL", "Brussels": europeanCapitals.append[]
        case "LIE", "Vaduz": europeanCapitals.append[]
        case "BGR", "Sofia": europeanCapitals.append[]
        case "USA", "Washington D.C": otherCapitals.append[]
        case "MEX", "Mexico City": otherCapitals.append[]
        case "BRA", "Brasilia": otherCapitals.append[]
        case "IND", "New Delhi": asianCapitals.append[]
        case "VNM", "Hanoi": asianCapitals.append[]

    }
    // End code
}

2 Answers

Hi Maxwell,

You are pretty much there with this. There's just a couple of points to fix.

First, switch just on the key. You want to append() (round brackets!) the value to the relevant array when the key matches. Pass the value into the append() method - arrayName.append(value).

You can also have multiple case matches.

So, here's a clue:

switch key{
  case "BEL", "LIE", "BGR": europeanCities,append(value)  
  // further cases here!
}

Think about the default case too.

Let me know how you get on!

Steve.

Maxwell Catmur
Maxwell Catmur
7,355 Points

Great! Thank you very much!

No problem! :+1: :smile:

Andrew Bergsma
Andrew Bergsma
880 Points

I'm stumped on this one.. I keep trying every which way and the compiler keeps returning the error "Expression pattern of type 'String' cannot match values of type '(key: String, value: String)" and extra call in argument. Please help! thanks

Can you post your code, Andrew?

Andrew Bergsma
Andrew Bergsma
880 Points

What am I doing wrong here? https://teamtreehouse.com/library/swift-collections-and-control-flow/control-flow-with-conditional-statements/working-with-switch-statements

var europeanCapitals: [String] = []
var asianCapitals: [String] = []
var otherCapitals: [String] = []

let world = [
  "BEL": "Brussels", 
  "LIE": "Vaduz", 
  "BGR": "Sofia", 
  "USA": "Washington D.C.", 
  "MEX": "Mexico City", 
  "BRA": "Brasilia", 
  "IND": "New Delhi", 
  "VNM": "Hanoi"]

for BEL in world {
    // Enter your code below
    switch BEL {
    case "BEL", "Brussels": europeanCapitals.append("Brussels", "Vaduz", "Sofia")
    case "LIE": europeanCapitals.append("Vaduz")
    case "BGR": europeanCapitals.append("Sofia")
    case "USA": otherCapitals.append("Washington D.C.")
    case "MEX": otherCapitals.append("Mexico City")
    case "BRA": otherCapitals.append("Brasilia")
    case "IND": asianCapitals.append("New Delhi")
    case "VNM": asianCapitals.append("Hanoi") 
    default: otherCapitals.append("country code does not exist")
    }
}

[MOD: edited code block - srh]

HI Andrew,

The posts in this thread cover your issue. But first, don't amend the code the challenge presents you with. Restart the challenge.

Then, just switch on the key and use append() to add the value to the respective array.

So you get:

for (key, value) in world{

}

Switch on key and append value. Like:

switch key{
  case "BEL", "LIE", "BGR": europeanCities,append(value)  
  // further cases here!
}

Make sense?

Steve.