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

Zheng Lai
Zheng Lai
2,271 Points
Posted by Zheng Lai
Zheng Lai
2,271 Points

for the following code in the for loop: europeanCapitals.append(world[key]) why wouldn't this line of code compile

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 {
    case "VNM","BEL","BGR" : europeanCapitals.append(world[key]);
    case "IND","VNM","LIE" : asianCapitals.append(value);
    default : otherCapitals.append(value);
    }
    // End code
}

In the above code, why " europeanCapitals.append(world[key]);" wouldn't compile?

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 {
    case "VNM","BEL","BGR" : europeanCapitals.append(value);
    case "IND","VNM","LIE" : asianCapitals.append(value);
    default : otherCapitals.append(key);
    }
    // End code
}

2 Answers

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Hi there,

You want to do exactly what you have done with the previous two cases; append the value.

Also, you need to include Vietnam only once, and move Liechtenstein back into Europe. :wink: 

  switch key {
    case "LIE","BEL","BGR" : europeanCapitals.append(value);
    case "IND","VNM" : asianCapitals.append(value);
    default : otherCapitals.append(value);
  }

I hope that helps,

Steve.

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Alternatively, you'll need to unwrap the dictionary element - dictionaries return optionals. So, to access world directly and for a second time given that the for loop is already managing this, you can use a bang:

    switch key {
      case "LIE","BEL","BGR" : europeanCapitals.append(world[key]!);
      case "IND","VNM" : asianCapitals.append(world[key]!);
      default : otherCapitals.append(world[key]!);
    }

That's not pretty but it would work. :smile:

Steve.