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
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
case let a as Cat:
label.text = 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
default:
break
}
I'm at my wits end. Could someone shed some light on this? Thanks.
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> 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
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
case let a as Cat:
label.text = 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
default:
break
}
I'm at my wits end. Could someone shed some light on this? Thanks.
_______________________________________________
swift-users mailing list
swift-users@swift.org https://lists.swift.org/mailman/listinfo/swift-users
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 <jens@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.
_______________________________________________
swift-users mailing list
swift-users@swift.org <mailto:swift-users@swift.org> https://lists.swift.org/mailman/listinfo/swift-users