no idea how to begin

Question

Here we have a dictionary of type [String: String] 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.
I've already set up the for in loop for you so jump right in!
```switch.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
// End code
}
```
Update: merged from second question
my code:
is it right? what are the problems?
swift
switch world {
case "BEL": europeanCapitals.append(value) 
case "LIE": europeanCapitals.append(value)
case "BGR": europeanCapitals.append(value)
case "IND": asianCapitals.append(value)
case "VNM": asianCapitals.append(value)
default: otherCapitals.append

Martin Wildfeuer · Accepted Answer

Hey there! The idea of your code is right, but what you pasted does not compile. It might just be a copy&paste error, so lets fix that first:
```swift
//...
for (key, value) in world {
    switch world {
    case "BEL": europeanCapitals.append(value)
    case "LIE": europeanCapitals.append(value)
    case "BGR": europeanCapitals.append(value)
    case "IND": asianCapitals.append(value)
    case "VNM": asianCapitals.append(value)
    default: otherCapitals.append(value) // .append(value) just as above
    } // Add missing closing bracket
}
```
What does not work, though, is switching over world directly this way. world is a dictionary containing a String key and a String value. By iterating over it for (key, value) in world this way, you have access to key and value in the body.
Check for the key as follows:
```swift
//...
for (key, value) in world {
    switch key { // change world to key
    case "BEL": europeanCapitals.append(value)
    case "LIE": europeanCapitals.append(value)
    case "BGR": europeanCapitals.append(value)
    case "IND": asianCapitals.append(value)
    case "VNM": asianCapitals.append(value)
    default: otherCapitals.append(value)
    }
}
```
Hope that helps :)

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Aditya Gawade

Aditya Gawade

no idea how to begin

1 Answer

Martin Wildfeuer

Martin Wildfeuer