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iOS Swift 2.0 Collections and Control Flow Control Flow With Conditional Statements Working with Switch Statements

Justin Bonaccorso
Justin Bonaccorso
2,781 Points
Posted by Justin Bonaccorso
Justin Bonaccorso
2,781 Points

To do this you're going to use a switch statement and switch on the key

The code challenges seem to be getting very complicated which is understandable, but in the videos we don't cover situations like this, and being a complete novice I get lost very quickly and then become frustrated that I don't have the resources in the videos to accurately address the problem. Any help would be greatly appreciated. I have tried a few different things, and nothing seems to work correctly.

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
    switch key in world {
    case "BEL": results.append = (europeanCapitols[])
    case "LIE": results.append(otherCapitals[])
    case "BGR": results.append(otherCapitals[])
    case "USA": results.append(otherCapitals[])
    case "MEX": results.append(otherCapitals[])
    case "BRA": results.append(otherCapitals[])
    case "IND": results.append(asianCapitals[])
    case "VNM": results.append(otherCapitals[])
    }
    // End code
}
gianpierovecchi
gianpierovecchi
15,043 Points

I don't remember the exercise but probably the idea is that you use switch to select which City is in which regions, and adding them to the respective array,

So the for loop gives you "key" and "value".

The correct answer should be something like:

for (key, value) in world {
    // Enter your code below
    switch key {
    case "BEL", "BGR", "LIE": europeanCapitals.append(value)
    case "VNM", "IND": asianCapitals.append(value)
    default: otherCapitals.append(value)
    }
    // End code
}

At the end of the for loop you will have the arrays full with the city names.

Enjoy

Justin Bonaccorso
Justin Bonaccorso
2,781 Points
Justin Bonaccorso
Justin Bonaccorso
2,781 Points

Makes sense Gianpiero, I kept getting stuck at the 'switch key' step before even going further into it. Thank you!

1 Answer

Greg Kaleka
Greg Kaleka
39,021 Points
Greg Kaleka
Greg Kaleka
39,021 Points

Hi Justin,

You're on the right track! Basically, what we want to do here is append the value to the correct array. Two things to remember (as an aside, remember you can always check the Apple documentation if you're not sure how a method works. This is a great habit to get into!):

  1. The append method works like this: nameOfArray.append(valueToAddToArray).
  2. One neat feature of switch statements is that you can combine cases if you're doing the same thing.

So putting these two things together, for the three european capitals, we can write:

switch.swift 
case "BEL", "LIE", "BGR":
      europeanCapitals.append(value)

Does that make sense? The last thing to remember is the default case. Since we have only three arrays to worry about, you can write two sets of cases, and then have the value appended to otherCapitals in the default case, like this:

default.swift 
default:
     otherCapitals.append(value)

I think you can put this all together. Let me know if you have trouble!

Happy coding :thumbsup:

-Greg

Justin Bonaccorso
Justin Bonaccorso
2,781 Points
Justin Bonaccorso
Justin Bonaccorso
2,781 Points

After reading it in this way, it is a lot less confusing. Sometimes I get mixed up with the if/else statements and switch statements, and this outlined it a lot better. Thank You!!!