Swift3：转换UIViewController子类失败

Question

I have a ViewController ( BViewController ) that's inheriting from another UIViewController Subclass ( AViewController ). (The reason I want to do this is I'm reusing the same view in storyboard 3+ times for different screens.)

When I call:

let storyboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
        let vc = storyboard.instantiateViewController(withIdentifier: "AViewController") as! BViewController
        self.show(vc, sender: self)

I get this error:

Could not cast value of type 'test.AViewController' (0x10d08b478) to 'test.BViewController' (0x10d08b3f0).

Here are my subclasses, they have nothing in them.

class AViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

-

class BViewController: AViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

The class in Storyboard is set to AViewController because I'm trying to share IBOutlets across all children without recreating the views. There is only one View Controller Scene in my UIStoryboard .

Answer 1

According to the answer in this thread, it isn't possible to reuse a single UIViewController Scene with multiple subclasses with UIStoryBoard. It is however possible with nib files.

How to use single storyboard uiviewcontroller for multiple subclass

Answer 2

You probably don't put the right view controller identifier:

let storyboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewController(withIdentifier: "BViewController") as! BViewController
self.show(vc, sender: self)

(BViewController instead of AViewController)

EDIT : Here's an example: I have a SignupVC view controller in my storyboard, but its storyboard ID is "signup_vc"

Answer 3

您必须在情节提要中将视图控制器的类设置为BViewController