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?

Answer 1

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()

Answer 2

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.