Howdy everyone. I've been looking at other solutions to this and am loving the various approaches people are coming up with.

I tried to do checkpoint 6 using an Error enum to reject a gear change which is out of range. In order to make the error message a little bit more contextual, I added an associated value to the enum but I don't know how to get at this associated value in the catch{} block.

Here's what I've got at the moment

import UIKit

enum CarError: Error {
    case gearNotAvailable (gear: Int)
}

struct Car {
    let numberOfGears: Int
    private(set) var currentGear: Int = 0 // 0=Neutral, -1=Reverse

    mutating func changeGear(newGear: Int) throws {
        if newGear < -1 || newGear > numberOfGears {
            throw CarError.gearNotAvailable(gear: newGear)
        }
        currentGear = newGear
        print("The car is now in gear \(currentGear)")
    }
}

var car = Car(numberOfGears: 3)

do {
    try car.changeGear(newGear: 3)
    try car.changeGear(newGear: 5)
} catch CarError.gearNotAvailable {
    print("You tried to change to a gear \(CarError.gearNotAvailable) which the car does not have")
}

The error message comes back as:

You tried to change to a gear (Function) which the car does not have

I'm struggling to find any examples online showing how to extract associated values from an error enum in a catch block. Is there a simple way to get at this value or is the solution going to be more convoluted than I imagined?

Fantastic! Many thanks :)