Returning the subclass in a UIViewController static

Question

Consider a base UIViewController class...

class Rooms: UIViewController {
    class func instantiate()->Rooms {
    }

    static func make()->Rooms {
         


        

Answer 1

I don't like to provide my own answer, but the solution is ..

So the problem is, at editor time

let d = Dining.make()

"doesn't work", you have to do this

let d = Dining.make() as! Dining

(It DOES work at compile time, d becomes a Dining: it doesn't "work" at editor time.)

So the solution is

static func make()->Rooms {
    let emplacedAndSetup = self.instantiate()
    return emplacedAndSetup
}

becomes

static func make<T: Rooms>()->T {
    let emplacedAndSetup = self.instantiate() as! T
    return emplacedAndSetup
}

So that's it.

Note - it's entirely possible AppzForLife's solution works and/or is better as a general purpose "UIViewController auto-instantiator", but this is the answer to the question per se.

Answer 2

You can do something like this.

class RoomBase: RoomProtocol {
    // things common to every room go here
    required init() {}
}

You can put in RoomBase all the stuff you want the other rooms to inherit.

Next you put the make() method into a protocol extension.

protocol RoomProtocol: class {
    init()
}

extension RoomProtocol where Self: RoomBase {
    static func make() -> Self {
        let room = Self()
        // set up
        return room
    }
}

Now you can write

class Dining: RoomBase {}
class Bath: RoomBase { }

And this code will work

let dining: Dining = Dining.make()
let bath: Bath = Bath.make()