WKWebView のクリック動作を最適化する

import GoogleMobileAds
import SafariServices
import WebKit

class ViewController: UIViewController, WKNavigationDelegate, WKUIDelegate {

  override func viewDidLoad() {
    super.viewDidLoad()

    // ... Register the WKWebView.

    // 1. Set the WKUIDelegate on your WKWebView instance.
    webView.uiDelegate = self;
    // 2. Set the WKNavigationDelegate on your WKWebView instance.
    webView.navigationDelegate = self
  }

  // Implement the WKUIDelegate method.
  func webView(
      _ webView: WKWebView,
      createWebViewWith configuration: WKWebViewConfiguration,
      for navigationAction: WKNavigationAction,
      windowFeatures: WKWindowFeatures) -> WKWebView? {
    // 3. Determine whether to optimize the behavior of the click URL.
    if didHandleClickBehavior(
        currentURL: webView.url,
        navigationAction: navigationAction) {
      print("URL opened in SFSafariViewController.")
    }

    return nil
  }

  // Implement the WKNavigationDelegate method.
  func webView(
      _ webView: WKWebView,
      decidePolicyFor navigationAction: WKNavigationAction,
      decisionHandler: @escaping (WKNavigationActionPolicy) -> Void)
  {
    // 3. Determine whether to optimize the behavior of the click URL.
    if didHandleClickBehavior(
        currentURL: webView.url,
        navigationAction: navigationAction) {
      return decisionHandler(.cancel)
    }

    decisionHandler(.allow)
  }

  // Implement a helper method to handle click behavior.
  func didHandleClickBehavior(
      currentURL: URL,
      navigationAction: WKNavigationAction) -> Bool {
    guard let targetURL = navigationAction.request.url else {
      return false
    }

    // Handle custom URL schemes such as itms-apps:// by attempting to
    // launch the corresponding application.
    if navigationAction.navigationType == .linkActivated {
      if let scheme = targetURL.scheme, !["http", "https"].contains(scheme) {
        UIApplication.shared.open(targetURL, options: [:], completionHandler: nil)
        return true
      }
    }

    guard let currentDomain = currentURL.host,
      let targetDomain = targetURL.host else {
      return false
    }

    // Check if the navigationType is a link with an href attribute or
    // if the target of the navigation is a new window.
    if (navigationAction.navigationType == .linkActivated ||
      navigationAction.targetFrame == nil) &&
      // If the current domain does not equal the target domain,
      // the assumption is the user is navigating away from the site.
      currentDomain != targetDomain {
      // 4. Open the URL in a SFSafariViewController.
      let safariViewController = SFSafariViewController(url: targetURL)
      present(safariViewController, animated: true)
      return true
    }

    return false
  }
}

@import GoogleMobileAds;
@import SafariServices;
@import WebKit;

@interface ViewController () <WKNavigationDelegate, WKUIDelegate>

@property(nonatomic, strong) WKWebView *webView;

@end

@implementation ViewController

- (void)viewDidLoad {
  [super viewDidLoad];

  // ... Register the WKWebView.

  // 1. Set the WKUIDelegate on your WKWebView instance.
  self.webView.uiDelegate = self;
  // 2. Set the WKNavigationDelegate on your WKWebView instance.
  self.webView.navigationDelegate = self;
}

// Implement the WKUIDelegate method.
- (WKWebView *)webView:(WKWebView *)webView
  createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration
             forNavigationAction:(WKNavigationAction *)navigationAction
                  windowFeatures:(WKWindowFeatures *)windowFeatures {
  // 3. Determine whether to optimize the behavior of the click URL.
  if ([self didHandleClickBehaviorForCurrentURL: webView.URL
      navigationAction: navigationAction]) {
    NSLog(@"URL opened in SFSafariViewController.");
  }

  return nil;
}

// Implement the WKNavigationDelegate method.
- (void)webView:(WKWebView *)webView
    decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction
                    decisionHandler:
                        (void (^)(WKNavigationActionPolicy))decisionHandler {
  // 3. Determine whether to optimize the behavior of the click URL.
  if ([self didHandleClickBehaviorForCurrentURL: webView.URL
      navigationAction: navigationAction]) {
    decisionHandler(WKNavigationActionPolicyCancel);
    return;
  }

  decisionHandler(WKNavigationActionPolicyAllow);
}

// Implement a helper method to handle click behavior.
- (BOOL)didHandleClickBehaviorForCurrentURL:(NSURL *)currentURL
                    navigationAction:(WKNavigationAction *)navigationAction {
  NSURL *targetURL = navigationAction.request.URL;

  // Handle custom URL schemes such as itms-apps:// by attempting to
  // launch the corresponding application.
  if (navigationAction.navigationType == WKNavigationTypeLinkActivated) {
    NSString *scheme = targetURL.scheme;
    if (![scheme isEqualToString:@"http"] && ![scheme isEqualToString:@"https"]) {
      [UIApplication.sharedApplication openURL:targetURL options:@{} completionHandler:nil];
      return YES;
    }
  }

  NSString *currentDomain = currentURL.host;
  NSString *targetDomain = targetURL.host;

  if (!currentDomain || !targetDomain) {
    return NO;
  }

  // Check if the navigationType is a link with an href attribute or
  // if the target of the navigation is a new window.
  if ((navigationAction.navigationType == WKNavigationTypeLinkActivated
      || !navigationAction.targetFrame)
      // If the current domain does not equal the target domain,
      // the assumption is the user is navigating away from the site.
      && ![currentDomain isEqualToString: targetDomain]) {
     // 4. Open the URL in a SFSafariViewController.
    SFSafariViewController *safariViewController =
        [[SFSafariViewController alloc] initWithURL:targetURL];
    [self presentViewController:safariViewController animated:YES
        completion:nil];
    return YES;
  }

  return NO;
}