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iosswiftinheritancesubclasssuperclass

cannot change superclass variable "description"

I'm trying to learn the concept of inheritance in Swift and have came up with the following code. I had no problem modifying variable "numberOfWheels" in the subclass, but when I tried to modify variable "description" in the subclass, Xcode display error: 

cannot assign to property "description" is a get only property

Because I'm relatively new to Swift, I am unable to solve this problem? Could someone please provide me with a code example of how to solve this problem? Thank you very much for any help!

class Vehicle{
    var numberOfWheels = 0
    var description: String{
        return "\(numberOfWheels) wheels"
    }
}

class Bicycle: Vehicle {
    override init(){
        super.init()
        numberOfWheels = 2
        description = "\(numberOfWheels) wheels, more is good"
    }
}

enter image description here

Solution

  • description is a read-only computed property and therefore cannot be directly assigned to. It is typically used to provide a String conversion for a class that implements CustomStringConveritble for printing purposes. If you truly want to override description in your subclass, you should do it as follows:

    override var decsription: String {
    return "\(numberOfWheels) wheels, more is good"
}