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iOS Swift Functions and Optionals Parameters and Tuples Tuples

Simon Pike
Simon Pike
1,415 Points
Posted by Simon Pike
Simon Pike
1,415 Points

What is an unused l-value?

The question asks me to : Create a variable named result and assign it the tuple returned from function greeting. (Note: pass the string "Tom" to the greeting function.)

I have copied my code into Xcode, and it seems to run OK, but does not compile in this test browser environment.

When I go to the Preview pane, it tells me that my expression resolves to an unused l-value.

What's that? and how can I resolve the issue?

tuples.swift 
func greeting(person: String) -> (greeting: String, language: String) {
    let language = ("English")
    let greeting = ("Hello \(person)", "speak \(language)")

    return greeting
}

 var result = greeting("Tom")

1 Answer

Richard Lu
Richard Lu
20,185 Points
Richard Lu
Richard Lu
20,185 Points

Hi Simon,

You have a very interesting solution (assigning it to a constant before returning it). The reason you may be getting the error is because the challenge expects a tuple value returned (with the 2nd value of the tuple with just the language). Here's the problem in your snippet of code

let greeting = ("Hello \(person)", "speak \(language)")   // this returns a tuple of the values ("Hello Tom", "speak English")

To fix this problem, remove the string "speak ". So you have:

let greeting = ("Hello \(person)", "\(language)")

Here's a more common way of solving this problem (reason why your solution is so unique):

func greeting(person: String) -> (greeting: String, language: String) {
    let language = "English"
    let greeting = "Hello \(person)"   // this is just the greeting string, instead of a tuple

    return (greeting, language)   // the return value is creating a tuple
}

var result = greeting("Tom")

Happy coding! :)

Simon Pike
Simon Pike
1,415 Points
Simon Pike
Simon Pike
1,415 Points

Thank you very much Richard! i have spent most of the afternoon trying variations on this!