I've seen a clearer solution to this checkpoint, but it was shifting gear by 1, and I created it so it can shift by any number unless it's higher/lower then the capabilities of that car. I think it's little bit more complicated but it works. Could someone tell me how can I write this code more efficiently and simpler ?

import UIKit

struct Car {

    let model: String
    let numberOfSeats: Int
    var currentGear = 0 {
        didSet {
            switch currentGear {
            case 1...10:
                print("You are now in gear \(currentGear)")
            case 0:
                print("You are now in neutral")
            default:
                print("I don't know in which gear you are in")
            }
        }
    }

    mutating func gearUp(by gear: Int) {
        switch currentGear + gear {
        case 1...10:
            self.currentGear += gear
        default:
            print("You cannot shift to this gear. This gear doesn't exist in your car")
        }
    }

    mutating func gearDown(by gear: Int) {
        switch currentGear {
        case 1...10:
            if currentGear >= gear {
                self.currentGear -= gear
            } else {
                print("You cannot shift down by \(gear) gear(s). Current gear is \(currentGear)")
            }
        case 0:
            print("You are already in neutral. Cannot shift down.")
        default:
            print("You cannot shift to this gear. This gear doesn't exist in your car")
        }
    }

}

var car = Car(model: "Porsche 911", numberOfSeats: 2, currentGear: 0)

car.gearUp(by: 10)

car.gearDown(by: 10)

Thank you all for answers...

Could someone tell me how can I write this code more efficiently and simpler ?

Jumping ahead a little bit, take a look at how you can remove this awkward code using inflection.

..... } else {
  //                                        👇🏼    Ugh!
  print("You cannot shift down by \(gear) gear(s). Current gear is \(currentGear)")
}

See -> Avoiding Optional Plurals

Keep Coding

Please return here and show us how you streamlined your code.

your thoughts

struct Car {
    let model: String
    let numberOfSeats: Int
    private(set) var currentGear: Int

    init(model: String, numberOfSeats: Int) {
        self.model = model
        self.numberOfSeats = numberOfSeats
        self.currentGear = 0
    }

    mutating func gearUpDown(state: String) {
        if state.lowercased() == "up" {
            if currentGear < 5 {
                currentGear += 1
            }
        } else {
            if currentGear > 0 {
                currentGear -= 1
            }
        }

    }
}