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iOS Functions in Swift Adding Power to Functions Returning Complex Values

Michael Bau
Michael Bau
3,394 Points
Posted by Michael Bau
Michael Bau
3,394 Points

Unsure how to use 'Double' values

Hi,

I can't get this to work. I am not sure of the syntax in the switch statement when trying switch on 'double' values'. How do you actually write it out? I have tried (among many others) with:

case "Eiffel Tower": (48.8582, 2.2945) (as an example), but that doesn't work

What is the correct syntax when dealing with doubles?

Furthermore, how do you return the values when you are not supposed to label the return arguments?

Best regards, Michael

functions.swift 
// Enter your code below

func coordinates(for location: String) -> (Double, Double) {


    switch location {
    case "Eiffel Tower": (48.8582, 2.2945)
    case "Great Pyramid": (29.9792, 31.1344)
    case "Sydney Opera House": (33.8587, 151.2140)
    default: (0.0)
    }

    return (location)
}

let locationResult = coordinates(for: "Eiffel Tower")

2 Answers

Steve Hunter
Steve Hunter
57,712 Points

Hi Michael,

You're pretty much right with that but you want to return your tuples, not location as that is what gets passed into the func.

So, just add a return in front of the tuples and remove your existing return line:

  switch location{
    case "Eiffel Tower": return (48.8582, 2.2945)
    case "Great Pyramid": return (29.9792, 31.1344)
    case "Sydney Opera House": return (33.8587, 151.2140)
    default: return (0, 0)
  }

So, the user passes in "Sydney Opera House" as the string, and the method returns the tuple, (Double, Double).

Make sense?

Steve.

Michael Bau
Michael Bau
3,394 Points
Michael Bau
Michael Bau
3,394 Points

Hi Steve,

Once again, thanks for your help! I wasn't aware that I were to return a value for each case, but now I know :o)

Best regards, Michael

Steve Hunter
Steve Hunter
57,712 Points

Hi Michael,

No problem - glad it made sense and you got through it.

Returning an unnamed thing can feel odd at times; we so often return a named constant or variable - and tuples are often an unfamiliar construct too, which can add to the confusion.

Giving it some thought, I wondered whether assigning the tuples to a variable/constant (a named thing) then returning that - would this add clarity, make the code more readable or just cut through some of the confusion? I don't think it did:

func coordinates(for location: String) -> (Double, Double) {
  let returnValue: (Double, Double)
  switch location{
    case "Eiffel Tower": returnValue = (48.8582, 2.2945)
    case "Great Pyramid": returnValue = (29.9792, 31.1344)
    case "Sydney Opera House": returnValue = (33.8587, 151.2140)
    default: returnValue = (0, 0)
  }
  return returnValue
}

I could probably (certainly!) have done a better job of naming that constant but I don't feel that this code is any clearer. The addition hasn't cut through the confusing areas, indeed, it has probably diverted attention away from where it is needed! It was worth a try, though. But, as is a common theme with my code, it failed to deliver anything better - these are just concepts that need familiarity to get through the confusion. Dressing the code up doesn't seem to, I don't think.

Your thoughts?

Steve.

Michael Hulet
Michael Hulet
47,912 Points
Michael Hulet
Michael Hulet
47,912 Points

There's nothing special about switching on Double values in Swift. In fact, your handling of all the Doubles looks just fine. The reason you're failing right now is because you're not actually doing anything with any of the values in the switch statement, but the challenge asks you to return them. Currently, your code doesn't do anything with any of the tuples it creates, and then returns the location parameter without modifying it. Instead, you need to write return before every tuple in the switch statement, and not at the bottom of the function. Lastly, you'll need to specify 0 twice in the default case, for both the latitude and longitude. You've left all the values in all your tuples unnamed so far like the challenge asks, so once you fix the problems mentioned above, you should pass the challenge. Great job!

Michael Bau
Michael Bau
3,394 Points
Michael Bau
Michael Bau
3,394 Points

Hi Michael,

Thanks a lot for your help. I guess I was too focused on the 'double' values there and forgot all about actually returning the values.

Best regards, Michael