swift - Initialize view controller from storyboard by overriding init

Question

I have a ViewController instance defined in a storyboard. I can initialize it by the following

var myViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("myViewControllerIdentifier") as! ViewController

Is there a way to override the init method of ViewController so that I can initialize it using

var myViewController = ViewController()

I tried overriding init

convenience init() {
    self = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("SearchTableViewController") as! SearchTableViewController
}

but the compiler doesn't like that. Any ideas?

It just looks cleaner I guess. Plus if the view is designed in a nib it works automatically so I can go from storyboards to nibs without changing the initialization code — adamF, Aug 05 '15 at 01:37
How about just creating a custom ViewController class for each ViewController that you have? That seems a lot cleaner to me. — Caleb, Aug 05 '15 at 01:43
That's what I did so far. ViewController is a custom subclass, but I still have to initialize it using the storyboard — adamF, Aug 05 '15 at 02:04
Just name it as the class of the Storyboard item and it's the same thing — Caleb, Aug 05 '15 at 02:06

score 32 · Accepted Answer · answered Aug 05 '15 at 20:54

A convenience initializer must always delegate to a designated initializer for the same class, and a designated initializer must call a superclass initializer.

Since the superclass doesn't have an appropriate initializer, you would probably be better served by a class factory method:

static func instantiate() -> SearchTableViewController
{
    return UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("SearchTableViewController") as! SearchTableViewController
}

then use:

var myViewController = SearchTableViewController.instantiate()

according to the swift api guidelines - factory methods should begin with "make". https://swift.org/documentation/api-design-guidelines/ — user1687195, Apr 27 '17 at 18:15

Berk · Answer 2 · 2018-08-13T18:38:31.700

A class factory method is the way to go for now. Here's a protocol that you can use to quickly add makeFromStoryboard support to all UIViewControllers.

protocol StoryboardInstantiable {

    static var storyboardName: String { get }
    static var storyboardBundle: NSBundle? { get }
    static var storyboardIdentifier: String? { get }
}

extension StoryboardInstantiable {

    static var storyboardBundle: NSBundle? { return nil }
    static var storyboardIdentifier: String? { return nil }

    static func makeFromStoryboard() -> Self {
        let storyboard = UIStoryboard(name: storyboardName, bundle: storyboardBundle)

        if let storyboardIdentifier = storyboardIdentifier {
            return storyboard.instantiateViewControllerWithIdentifier(storyboardIdentifier) as! Self
        } else {
            return storyboard.instantiateInitialViewController() as! Self
        }
    }
}

Example:

extension MasterViewController: StoryboardInstantiable {

    static var storyboardName: String { return "Main" }
    static var storyboardIdentifier: String? { return "Master" }
}

In case the view controller is the initial view controller in the storyboard, you can simply ignore storyboardIdentifier.

In case all the view controllers are in the same storyboard, you can also override storyboardName under the StoryboardInstantiable extension and return the name.

score 0 · Answer 3 · answered Aug 25 '20 at 03:39

You can try Generics. Like this:

func Tvc<T>(_ vcType: T.Type) -> T {
    let vc = (vcType as! UIViewController.Type).vc//限制或明确为 UIViewController.Type
    return vc as! T
}

extension UIViewController {
    fileprivate static var vc: UIViewController {
        let M = UIStoryboard.init(name: "V", bundle: Bundle.main)
        return M.instantiateViewController(withIdentifier: "\(self)")
    }
}

Example

let vc = Tvc(HLCases.self)
_vc.navigationController?.pushViewController(vc, animated: true)

swift - Initialize view controller from storyboard by overriding init

3 Answers3

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