Yes, not all animals have names.
Defining a protocol sounds reasonable.
In my case, the Animal, Dog and Cat are all subclasses of Core Data's
NSManagedObject, having to define a protocol and make them conform to that is a
bit involved.
But I think that seems to be the only sensible way.
Thanks.
> On 9 Jun 2017, at 7:28 PM, Jens Persson <j...@bitcycle.com> wrote:
>
> I'm not sure what you are trying to achieve.
> Why can't you just do:
> label.text = animal.nam
> ?
> Is it because not all Animals have names?
> If so, you could perhaps use something like this:
>
> class Animal {}
> protocol Named {
> var name: String { get }
> }
> class Dog: Animal, Named {
> let name = "Dog"
> }
> class Cat: Animal, Named {
> var name: String {
> return "Cat"
> }
> }
>
> let animals: [Animal] = [Cat(), Dog()]
>
> for animal in animals {
> if let namedAnimal = animal as? Named {
> print(namedAnimal.name)
> }
> }
>
>
>
>
> On Fri, Jun 9, 2017 at 12:34 PM, Glen Huang via swift-users
> <swift-users@swift.org <mailto:swift-users@swift.org>> wrote:
> Hi, I wonder what's the correct way to express something like this in swift:
>
> Say I have a superclass with two subclasses:
>
> class Animal {}
> class Dog: Animal {
> let name = "Dog"
> }
> class Cat: Animal {
> var name: String {
> return "Cat"
> }
> }
>
> And I want to display the name with a switch:
>
> switch animal {
> case let a as Dog, let a as Cat:
> label.text = a.name <http://a.name/>
> default:
> break
> }
>
> Swift currently won't allow me to use multiple value-binding patterns like
> this. I wonder what's the right way to express it? Must I repeat the
> statements?
>
> switch animal {
> case let a as Dog:
> label.text = a.name <http://a.name/>
> case let a as Cat:
> label.text = a.name <http://a.name/>
> default:
> break
> }
>
> I also tried fallthrough, but swift won't let me fall through to a
> value-binding pattern:
>
> switch animal {
> case let a as Dog:
> fallthrough // error
> case let a as Cat:
> label.text = a.name <http://a.name/>
> default:
> break
> }
>
> I'm at my wits end. Could someone shed some light on this? Thanks.
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