https://stackoverflow.com/questions/54678886/how-can-i-create-a-subclass-object

Knight.swift

// if Knight is just initializing the properties of its super class, you can omit 
// the init method entirely, and it will inherit it from its superclass

class Knight: Unit {

//     override init(pHealthPoints: Int, pDamage: Int, pMovement: Int) {
//         self.healthPoints = pHealthPoints
//         self.damage = pDamage
//         self.movement = pMovement
//     }

}

// If, on the otherhand, `Knight` really need to have some of its own properties,
// as well, then set the subclasses' properties and then call `super.init`

class Knight: Unit {
    let name: String
    
    init(name: String, pHealthPoints: Int, pDamage: Int, pMovement: Int) {
        self.name = name
        super.init(pHealthPoints: pHealthPoints, pDamage: pDamage, pMovement: pMovement)
    }

}