HomeVC.swift

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        switch segue.identifier ?? "" {
            //FIXME: 這裡有問題 可能是這邊造成retain cycle
        case "Web":
            if let indexPath = sender as? IndexPath {
                let row = indexPath.row
                if row == 0 {
                    guard let nav = segue.destination as? UINavigationController, let vc = nav.topViewController as? WebVController else { return }
                    vc.urlString = "http://www.kff.tw"
                    vc.navigationItem.title = "高雄電影節"
                }
                if row == 1 {
                    guard let nav = segue.destination as? UINavigationController, let vc = nav.topViewController as? WebVController else { return }
                    vc.urlString = "http://kfa.kcg.gov.tw/mobile/index.php"
                    vc.navigationItem.title = "高雄市電影館"
                }
            }
            if let banner = sender as? Banner {
                guard let nav = segue.destination as? UINavigationController, let vc = nav.topViewController as? WebVController else { return }
                vc.urlString = banner.Url
                if banner.PromoBannerName != "" {
                    vc.title = banner.PromoBannerName
                }
            }
        default: ()
        }
    }

WebVController.swift

import UIKit

class WebVController: UIViewController {
    @IBOutlet weak var webView: UIWebView!
    @IBOutlet weak var activityIndicatorView: UIActivityIndicatorView!
        
    var urlString: String? = nil

    // MARK: - Private var
    let iPad = UIDevice.current.userInterfaceIdiom == .pad

    // MARK: - UIViewController
    override var supportedInterfaceOrientations : UIInterfaceOrientationMask {
        if iPad {
            return .all
        } else {
            return .portrait
        }
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        if (urlString ?? "") != "" {
            if let _urlString = urlString {
            let url = URL (string: _urlString)
            let request = URLRequest(url: url!)
            webView.loadRequest(request)
            }
        } else {
            activityIndicatorView.isHidden = true
            view.addToBeSuppliedView()
        }
    }
    deinit {
        urlString = nil
        print("WebVC deinit.")
    }
    fileprivate func checkCanBack() {
        navigationItem.leftBarButtonItem?.isEnabled = webView.canGoBack
    }
    
    

    @IBAction func btnDismissTapped(_ sender: AnyObject) {
         //FIXME: 有問題 解散後還是被持有
        dismiss(animated: true, completion: nil)
    }
    
}
// MARK: - UIWebViewDelegate
extension WebVController: UIWebViewDelegate {
    func webViewDidStartLoad(_ webView: UIWebView) {
        activityIndicatorView.isHidden = false
        checkCanBack()
    }
    
    func webViewDidFinishLoad(_ webView: UIWebView) {
        delay(1) {
            self.activityIndicatorView.isHidden = true
        }
        checkCanBack()
    }
    
    func webView(_ webView: UIWebView, didFailLoadWithError error: Error) {
        activityIndicatorView.isHidden = true
        if (urlString ?? "") != "" {
            webView.addToBeSuppliedView(forText: "無法載入網頁")
        } else {
            checkCanBack()
        }
    }
    
    func webView(_ webView: UIWebView, shouldStartLoadWith request: URLRequest, navigationType: UIWebViewNavigationType) -> Bool {
        return true
    }
}