May I please have help in fixing these 5 errors in Xcode?

I was wondering if you would be able to help me with 5 errors that I am getting in the code that I am writing in Xcode using Swift. The 5 errors are cannot capture 'openPage' before it is declared, '(WKWebView, didFinishNavigation: WKNavigation!) → ()' does not have a member named 'loadRequest' (2 errors), cannot capture 'webView' before it is declared and '(WKWebView, didFinishNavigation: WKNavigation!) → ()' does not have a member named 'allowsBackForwardNavigationGestures'. I will attach the code below the question. Thanks if anyone can help.

Best Regards,

-Comm.Dan

import UIKit
import WebKit
class ViewController: UIViewController, WKNavigationDelegate {

    overridefunc viewDidLoad() {
        super.viewDidLoad()
        func openTapped() {
            let ac = UIAlertController(title: "Open page…", message: nil, preferredStyle: .ActionSheet)
            ac.addAction(UIAlertAction(title: "apple.com", style: .Default, handler: openPage))
            ac.addAction(UIAlertAction(title: "slashdot.org", style: .Default, handler: openPage))
            ac.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: nil))
            presentViewController(ac, animated: true, completion: nil)
        }
        func openPage(action: UIAlertAction!) {
            let url = NSURL(string: "http:/
            webView.loadRequest(NSURLRequest(URL: url))
        }
        func webView(webView: WKWebView, didFinishNavigation navigation: WKNavigation!) {
            title = webView.title
        }

      
        navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Open", style: .Plain, target: self, action: "openTapped")
        let url = NSURL(string: "http:/
        webView.loadRequest(NSURLRequest(URL: url))
        webView.allowsBackForwardNavigationGestures = true
      

        /
    }
  
    var webView: WKWebView!
    overridefunc loadView() {
        webView = WKWebView()
        webView.navigationDelegate = self
        view = webView
    }

    overridefunc didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        /
    }

}