Swift, creating a Generic UIViewController

Question

I am trying to create a Class like this :

class MyClass<T:UIView>: UIViewController{


    override init()
    {
        super.init(nibName: nil, bundle: nil);
    }

    required init(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func loadView() {
        self.view = T();
        println("loadView")
    }

    override func viewDidLoad() {
        super.viewDidLoad();
        println("viewDidLoad")
    }

}

When I want to use my class like that :

self.navigationController?.pushViewController(MyClass<UIView>(), animated: true)

The methods viewDidLoad and loadView are never called !!!

Do you know why and if there is some way of doing what I want.

Thanks in advance.

does your navigationController exist? Do you see the push happen on the screen? — Bartek Chlebek, Nov 18 '14 at 14:45
See this related question: http://stackoverflow.com/q/26097581/3804019 — rintaro, Nov 18 '14 at 15:05
@Bartek : Yes the navigationController exist, the push happen. — Fred, Nov 19 '14 at 08:17
@rintaro : Thanks, probably something like that. Finally Swift generics have lot of limitation ... quite disapointed — Fred, Nov 19 '14 at 08:19
Bumping in the same problem. Too bad that this doesn't work. — Wim Haanstra, May 21 '15 at 18:48
@Fred yes right? Protocols also don't support generics yet which is kinda crazy, breaks everything... (and I'm writing this after the release of Swift 2.0). — User, Jul 07 '15 at 19:58

rintaro · Answer 1 · 2014-11-19T08:34:23.970

As mentioned in OP comments, Generic class cannot be properly represented in Objective-C.

The workaround would be using the class as a property. something like this:

class MyClass: UIViewController{

    let viewCls:UIView.Type

    init(viewCls:UIView.Type = UIView.self) {
        self.viewCls = viewCls
        super.init(nibName: nil, bundle: nil);
    }

    required init(coder aDecoder: NSCoder) {
        self.viewCls = UIView.self
        super.init(coder: aDecoder)
    }

    override func loadView() {
        self.view = viewCls();
        println("loadView")
    }

    override func viewDidLoad() {
        super.viewDidLoad();
        println("viewDidLoad")
    }

}

// and then
self.navigationController?.pushViewController(MyClass(viewCls: UIView.self), animated: true)

Swift, creating a Generic UIViewController

1 Answers1