Hi is there anybody who is familiar with solving the function problem that can can help me please ?

It work and I differently see my mistakes now and will go back and practice more, Thanks for your help Matthew!

ahhh I forgot to use the word return by default, otherwise, I did the exact same as you.

We need to return the latitude and longitude value of a particular location. In Swift, to return two separate values of a function we need to use a tuple. We don't have to use a tuple if we only need one value returned.

In our declaration of the function, we specified that this function is returning a tuple consisting of two Doubles:

-> (Double, Double)

Therefore, in our return statement, the function is expecting to return only a tuple consisting of two Double values. If we didn't return exactly that, we would get an error.

To recall the value of that tuple, we just have to use dot notation after the variable name that stores the returned value (similar to accessing an instance's class/struct properties). In the code I typed up, you would use .0 and .1 to access the latitude and longitude properties, respectively. Like so:

let coordinates = getTowerCoordinates("Eiffel Tower")

print(coordinates.0) //Prints out "48.8582"
print(coordinates.1) //Prints out "2.2945"

While the code I posted in my initial response functionally works and completes the challenge, it would be better to name those tuple values to better understand what those values represent. In that case, I would change the function declaration to this:

func getTowerCoordinates(location: String) -> (latitude: Double, longitude: Double)

Then, I can access the tuple's values by doing this:

let coordinates = getTowerCoordinates("Eiffel Tower")

print(coordinates.latitude) //Prints out "48.8582"
print(coordinates.longitude) //Prints out "2.2945"

Source: Functions "Functions with Multiple Return Values" and The Basics "Tuples"

Given the current function declaration, our return type is a tuple consisting of two Double values. Therefore, we have to return a tuple consisting of two Double values. We always have to return whatever we declare as the return type in our function.

However, we can make the return type an OPTIONAL tuple instead by placing a '?' after the tuple in our function declaration. By doing this, we can return nil for the default clause in our switch statement instead of a value. The function would look like this:

func getTowerCoordinates(location: String) -> (latitude: Double, longitude: Double)? {
    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 nil
    }
}

When we make the function call, we can check if the function returns a value or nil. If the function returns nil, we can print out the statement "The value you entered does not exist". An example of this function call would be as follows:

if let coordinates = getTowerCoordinates("Tower of Terror") { 
     //If we get a coordinate tuple response, we handle that response in here...
} else {
     //If we get nil as a response...
     print("The value you entered does not exist")
}

For a more advanced concept, we could throw an error. I would say it's excessive for this scenario, but is useful for functions that could have multiple reasons why a valid value could not be returned. I'll include a link about it below.

Related Information:

The Swift Programming Language - The Basics - Optionals

The Swift Programming Language - Error Handling