CODEWITHSUNDEEP
swiftinheritanceenumsoverridingswift5
Malhar
Malhar

Reputation: 23

Swift : How to use enum variable from super class?

I have been trying to inherit and assign a value to my enum variable but it shows me following error everytime.

Following is sample source code (actual code I cannot post here)

Cannot override with a stored property animalType

class Animals : Livingrhings {
    var canFly = false
    enum AnimalsType {
        case underwater
        case soil
        case none
    }

}


class Wild : Animals {
    var animalType : AnimalsType = .none

}

class Crocodile : Wild {
    override var animalType: Animals.AnimalsType = .underwater // Error line
}

Here is ref. snapshot of my playground code.

enter image description here

Upvotes: 2

Views: 732

Answers (2)

vrutberg
vrutberg

Reputation: 2048

This has nothing to do with the fact that it's an enum type. Swift doesn't support overriding stored properties. I'd say you have two options here:

Making it a computed property 

class Wild : Animals {
    var animalType: AnimalsType { .none }
}

class Crocodile : Wild {
    override var animalType: Animals.AnimalsType { .underwater }
}

The reason this works is because computed properties can be overridden. Overriding a computed property arguably makes a bit more sense than overriding a stored property, because after all, stored properties don't really have anything to override. They're just values.

Make it part of an initializer

class Animals {
    var canFly = false
    let animalType: AnimalsType

    init(animalType: AnimalsType) {
        self.animalType = animalType
    }

    enum AnimalsType {
        case underwater
        case soil
        case none
    }
}

class Wild: Animals {
    convenience init() {
        self.init(animalType: .none)
    }
}

class Crocodile: Wild {
    convenience init() {
        self.init(animalType: .underwater)
    }
}

Depending on what you want to achieve either way might be better suited to your needs.

Upvotes: 3

Arkku
Arkku

Reputation: 42139

It looks like the value depends on the class, i.e., you don't need to change its value during the lifetime of an instance. If this is the case, you can change it to a computed property:

var animalType: AnimalsType { return .none }

And

override var animalType: AnimalsType { return .underwater }

Another possibility is to define the stored property once and assign the initial value in init for each class.

Upvotes: 2

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