errors creating a delegate from UISplitViewDetail to master in Swift

问题

SWIFT / IOS 8.2 I am trying to set my CalculatorViewController as the delegate target so I can get data - but I seem to be setting it wrong: "EXC_BAD_ACCESS (code:2)"

(in GraphView.swift)

protocol CalculatorViewDataSource: class {
    func calculateYForXEquals(sender: CalculatorViewController, currentX: CGFloat) ->CGFloat?
}

class GraphView: UIView {
    weak var calculatorViewDataSource: CalculatorViewDataSource?
    //...
}

(in GraphViewController.swift)

class GraphViewController: UIViewController {
    @IBOutlet weak var graphView: GraphView! {
        didSet{
            graphView.calculatorViewDataSource = self.view.superview?.superview as CalculatorViewController
        }
    }
// ...
}

(in CalculatorViewController.swift)

class CalculatorViewController: UIViewController, CalculatorViewDataSource{
    // ...
}

func calculateYForXEquals(sender: CalculatorViewController, currentX: CGFloat) ->CGFloat? {
    return nil
}

Issues:

I get a crash with a "EXC_BAD_ACCESS (code:2)" error when I try to set the delegate in the GraphViewController... Any idea why?

I don't know how to get to the class from the CalculatorViewController level. Here's the storyboard:

-> SplitViewController - NavigationController - (Master) CalculatorViewController
         I
     NavigationController - (Detail) GraphViewController

回答1:

Try to do something like this:

    var graphViewController: GraphViewController?

    private func setupSplitViewController() {
        let masterNavigationController: AnyObject? = splitViewController?.viewControllers.first
        graphViewController = masterNavigationController!.topViewController as? GraphViewController
        graphViewController!.graphView.calculatorViewDataSource = self
    }

来源：https://stackoverflow.com/questions/31528349/errors-creating-a-delegate-from-uisplitviewdetail-to-master-in-swift