UIMenuItem #selector method crash in wkwebview

Question

UIMenuItem selector method crashes in iOS 11 beta SDK.

-[WKContentView highlightText]: unrecognized selector sent to instance 0x7f85df8f3200

Method Definition:

func highlightText() 
{
  //
}

I try to add UIMenuItem in WKWebView,

let menuItemHighlight = UIMenuItem.init(title: "Highlight", action: #selector(ContentWebkitView.highlightText))
UIMenuController.shared.menuItems = [menuItemHighlight]

Answer 1

OK, we finally made it work for Swift 4:

1. In your WKWebView subclass, add the following property and method:

   // MARK: - Swizzling to avoid responder chain crash    
   var wkContentView: UIView? {
       return self.subviewWithClassName("WKContentView")
   }
   
   
   private func swizzleResponderChainAction() {
       wkContentView?.swizzlePerformAction()
   }
   

2. Then, add an extension to UIView (I put it in the same file as my WKWebView subclass, you can make it fileprivate if you'd like)

   // MARK: - Extension used for the swizzling part linked to wkContentView 
   extension UIView {
   
       /// Find a subview corresponding to the className parameter, recursively.
       func subviewWithClassName(_ className: String) -> UIView? {
   
           if NSStringFromClass(type(of: self)) == className {
               return self
           } else {
               for subview in subviews {
                   return subview.subviewWithClassName(className)
               }
           }
           return nil
       }
   
       func swizzlePerformAction() {
           swizzleMethod(#selector(canPerformAction), withSelector: #selector(swizzledCanPerformAction))
       }
   
       private func swizzleMethod(_ currentSelector: Selector, withSelector newSelector: Selector) {
           if let currentMethod = self.instanceMethod(for: currentSelector),
               let newMethod = self.instanceMethod(for:newSelector) {
               let newImplementation = method_getImplementation(newMethod)
               method_setImplementation(currentMethod, newImplementation)
           } else {
               print("Could not find originalSelector")
           }
       }
   
       private func instanceMethod(for selector: Selector) -> Method? {
           let classType = type(of: self)
           return class_getInstanceMethod(classType, selector)
       }
   
       @objc private func swizzledCanPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
           return false
       }
   }
   

Now the UIMenuItem works as expected:

But honestly, this really feels like a hack, and I would love Apple to fix this issue :-/

Thanks for Stephan Heilner for his answer: https://stackoverflow.com/a/42985441/4670400

Answer 2

I was also getting this error when I was overriding canPerformAction and checking for my custom selector. In my case I wanted to remove all menu items except for my custom one and the following made this work for me.

class ViewController: UIViewController {

    @IBOutlet weak var webView: MyWebView!

    override func viewDidLoad() {
        super.viewDidLoad()

        loadWebView()
        setupCustomMenu()
    }

    func loadWebView() {
        let url = URL(string: "http://www.google.com")
        let request = URLRequest(url: url!)
        webView.load(request)
    }

    func setupCustomMenu() {
        let customMenuItem = UIMenuItem(title: "Foo", action:
            #selector(ViewController.customMenuTapped))
        UIMenuController.shared.menuItems = [customMenuItem]
        UIMenuController.shared.update()
    }

    @objc func customMenuTapped() {
        let yay = "                                                                    

                                                        
            

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