Base class static method returns type of subclass in Swift - swift

Question

I want to have a base class static method which returns an array of the subclass type. Here is my current implementation. It works, but I have a small problem with it.
class Animal {
required init() { }
public static func generateMocks<T: Animal>() -> [T] {
var mocks: [T] = []
// some implementation goes here...
for _ in 0..<10 {
mocks.append( T() )
}
//
return mocks
}
}
let myMockAnimals: [Animal] = Animal.generateMocks() // this gives me type [Animal]
class Dog: Animal {
// dog things
var isCute = true
}
let myMockDogs: [Dog] = Dog.generateMocks() // this gives me type [Dog]
print(myMockDogs.first?.isCute) // true
/* My problem is that it is very annoying to have to declare my
myMockDogs variable as type "[Dog]". I would like it to
automatically infer this type. Like this: */
let myMockDogs2 = Dog.generateMocks() // oh no! It gives me type [Animal]
print(myMockDogs2.first?.isCute) // error! Value of type 'Animal' has no member 'isCute'
if let dog = myMockDogs2.first! as Dog { // error! 'Animal' is not convertible to 'Dog';
print(dog)
}
So my generic static function generateMocks is able to return the correct subclass when I specify the type of object I am expecting, like let myMockDogs2: [Dog] =..., but when I drop the explicit type I am expecting like in let myMockDogs2 =... then it suddenly goes back to using Animal as the type used for the generic function resulting in an array [Animal].
Is there a way to modify the generateMocks function which would cause let myMockDogs2 = Dog.generateMocks() to use type Dog for the generic T automatically?
You can copy this code into a Playground too! It works there! I'm really scared there's no solution to this, but maybe a Swift genius out there has an idea.

Answer 1

A possible solution is a protocol extension
protocol Animal {
init()
static func generateMocks() -> [Self]
}
extension Animal {
static func generateMocks() -> [Self] {
var mocks: [Self] = []
// some implementation goes here...
for _ in 0..<10 {
mocks.append( Self() )
}
//
return mocks
}
}
struct Dog: Animal {
// dog things
var isCute = true
}
let myMockDogs = Dog.generateMocks()
print(myMockDogs.first?.isCute) // true