Override static var in a child Class Swift

Question

To factorize my code, I want to set a stringKey from an Child class which I'll get in a class func in the parent class:

Chair.request();
Table.request();

class Furniture: NSObject {

    static let requestKey : String!

    class func request(){

        print("class key => \(self.requestKey)")
        ...
    }
}

class Chair: Furniture {
    static let requestKey : String = "jsonchairs"
} 

class Table: Furniture {
    static let requestKey : String = "tables"
} 

Of course, I have the precompiled error message

Property does not override any property from its superclass

Is there a solution to do this, or do I need to pass the key as parameter? like this:

Chair.request(key : "jsonchairs" );
Table.request(key : "tables" );

Answer 1

Just had the same problem. Use computed properties - these can be overriden.

Base class:

class BaseLanguage {
    class var language: String {
        return "Base"
    }

    static func getLocalized(key: String) -> String {
        print("language: \(language)");
    }
}

Child class:

class German: BaseLanguage {
    override class var language: String {
        return "de"
    }
}

If you can't use computed properties for some reason, you can always wrap variable properties in private singleton. The class exposes external interface as as static, but inside it has static private reference to its instance. You can change value of any property (as long as it's variable) within init method.

Answer 2

You can use protocols for that. Just make them both conform to RequestKeyProtocol fir example and than implement it in each case.

protocol RequestKeyProtocol {
 var requestKey: String
}




 class myClass: RequestKeyProtocol {
   var requestKey = "myKey"
   }

If you need a default value look into protocols extensions. Take a look at this year WWDC video about protocols as well.