Swift Protocol get only settable?

Question

why can I do this without any error:

var testDto = ModelDto(modelId: 1)
testDto.objectId = 2

while I define this:

protocol          


        

Answer 1

The behavior you are seeing on your code sample is called member hiding. Member hiding happens in object oriented languages when new a member is declared with the same name or signature of an inherited one, so by having: var objectId: Int in your struct implementation, you are effectively creating a new member called objectId and hiding the property inherited from the protocol.

In order to honor the contract between your struct and your protocol, objectId could be declared as:

  let objectId: Int = 1

or

var objectId: Int {
        get {
            return 1
        }
    }