react-native-webview/ios/RNCWKWebView.m

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#import "RNCWKWebView.h"
#import <React/RCTConvert.h>
#import <React/RCTAutoInsetsProtocol.h>
#import "RNCWKProcessPoolManager.h"
#import <UIKit/UIKit.h>

#import "objc/runtime.h"

static NSTimer *keyboardTimer;
static NSString *const MessageHandlerName = @"ReactNativeWebView";
static NSURLCredential* clientAuthenticationCredential;

// runtime trick to remove WKWebView keyboard default toolbar
// see: http://stackoverflow.com/questions/19033292/ios-7-uiwebview-keyboard-issue/19042279#19042279
@interface _SwizzleHelperWK : NSObject @end
@implementation _SwizzleHelperWK
-(id)inputAccessoryView
{
  return nil;
}
@end

@interface RNCWKWebView () <WKUIDelegate, WKNavigationDelegate, WKScriptMessageHandler, UIScrollViewDelegate, RCTAutoInsetsProtocol>
@property (nonatomic, copy) RCTDirectEventBlock onLoadingStart;
@property (nonatomic, copy) RCTDirectEventBlock onLoadingFinish;
@property (nonatomic, copy) RCTDirectEventBlock onLoadingError;
@property (nonatomic, copy) RCTDirectEventBlock onLoadingProgress;
@property (nonatomic, copy) RCTDirectEventBlock onShouldStartLoadWithRequest;
@property (nonatomic, copy) RCTDirectEventBlock onMessage;
@property (nonatomic, copy) WKWebView *webView;
@end

@implementation RNCWKWebView
{
  UIColor * _savedBackgroundColor;
  BOOL _savedHideKeyboardAccessoryView;
  BOOL _savedKeyboardDisplayRequiresUserAction;
}

- (instancetype)initWithFrame:(CGRect)frame
{
  if ((self = [super initWithFrame:frame])) {
    super.backgroundColor = [UIColor clearColor];
    _bounces = YES;
    _scrollEnabled = YES;
    _showsHorizontalScrollIndicator = YES;
    _showsVerticalScrollIndicator = YES;
    _directionalLockEnabled = YES;
    _automaticallyAdjustContentInsets = YES;
    _contentInset = UIEdgeInsetsZero;
    _savedKeyboardDisplayRequiresUserAction = YES;
  }

  // Workaround for a keyboard dismissal bug present in iOS 12
  // https://openradar.appspot.com/radar?id=5018321736957952
  if (@available(iOS 12.0, *)) {
    [[NSNotificationCenter defaultCenter]
      addObserver:self
      selector:@selector(keyboardWillHide)
      name:UIKeyboardWillHideNotification object:nil];
    [[NSNotificationCenter defaultCenter]
      addObserver:self
      selector:@selector(keyboardWillShow)
      name:UIKeyboardWillShowNotification object:nil];
  }

  return self;
}

- (void)dealloc
{
  [[NSNotificationCenter defaultCenter] removeObserver:self];
}

/**
 * See https://stackoverflow.com/questions/25713069/why-is-wkwebview-not-opening-links-with-target-blank/25853806#25853806 for details.
 */
- (WKWebView *)webView:(WKWebView *)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures
{
  if (!navigationAction.targetFrame.isMainFrame) {
    [webView loadRequest:navigationAction.request];
  }
  return nil;
}

- (void)didMoveToWindow
{
  if (self.window != nil && _webView == nil) {
    WKWebViewConfiguration *wkWebViewConfig = [WKWebViewConfiguration new];
    if (_incognito) {
      wkWebViewConfig.websiteDataStore = [WKWebsiteDataStore nonPersistentDataStore];
    } else if (_cacheEnabled) {
      wkWebViewConfig.websiteDataStore = [WKWebsiteDataStore defaultDataStore];
    }
    if(self.useSharedProcessPool) {
      wkWebViewConfig.processPool = [[RNCWKProcessPoolManager sharedManager] sharedProcessPool];
    }
    wkWebViewConfig.userContentController = [WKUserContentController new];

    if (_messagingEnabled) {
      [wkWebViewConfig.userContentController addScriptMessageHandler:self name:MessageHandlerName];

      NSString *source = [NSString stringWithFormat:
        @"window.%@ = {"
         "  postMessage: function (data) {"
         "    window.webkit.messageHandlers.%@.postMessage(String(data));"
         "  }"
         "};", MessageHandlerName, MessageHandlerName
      ];

      WKUserScript *script = [[WKUserScript alloc] initWithSource:source injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES];
      [wkWebViewConfig.userContentController addUserScript:script];
    }

    wkWebViewConfig.allowsInlineMediaPlayback = _allowsInlineMediaPlayback;
#if WEBKIT_IOS_10_APIS_AVAILABLE
    wkWebViewConfig.mediaTypesRequiringUserActionForPlayback = _mediaPlaybackRequiresUserAction
      ? WKAudiovisualMediaTypeAll
      : WKAudiovisualMediaTypeNone;
    wkWebViewConfig.dataDetectorTypes = _dataDetectorTypes;
#else
    wkWebViewConfig.mediaPlaybackRequiresUserAction = _mediaPlaybackRequiresUserAction;
#endif

    if(_sharedCookiesEnabled) {
      // More info to sending cookies with WKWebView
      // https://stackoverflow.com/questions/26573137/can-i-set-the-cookies-to-be-used-by-a-wkwebview/26577303#26577303
      if (@available(iOS 11.0, *)) {
        // Set Cookies in iOS 11 and above, initialize websiteDataStore before setting cookies
        // See also https://forums.developer.apple.com/thread/97194
        // check if websiteDataStore has not been initialized before
        if(!_incognito && !_cacheEnabled) {
          wkWebViewConfig.websiteDataStore = [WKWebsiteDataStore nonPersistentDataStore];
        }
        for (NSHTTPCookie *cookie in [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookies]) {
          [wkWebViewConfig.websiteDataStore.httpCookieStore setCookie:cookie completionHandler:nil];
        }
      } else {
        NSMutableString *script = [NSMutableString string];

        // Clear all existing cookies in a direct called function. This ensures that no
        // javascript error will break the web content javascript.
        // We keep this code here, if someone requires that Cookies are also removed within the
        // the WebView and want to extends the current sharedCookiesEnabled option with an
        // additional property.
        // Generates JS: document.cookie = "key=; Expires=Thu, 01 Jan 1970 00:00:01 GMT;"
        // for each cookie which is already available in the WebView context.
        /*
        [script appendString:@"(function () {\n"];
        [script appendString:@"  var cookies = document.cookie.split('; ');\n"];
        [script appendString:@"  for (var i = 0; i < cookies.length; i++) {\n"];
        [script appendString:@"    if (cookies[i].indexOf('=') !== -1) {\n"];
        [script appendString:@"      document.cookie = cookies[i].split('=')[0] + '=; Expires=Thu, 01 Jan 1970 00:00:01 GMT';\n"];
        [script appendString:@"    }\n"];
        [script appendString:@"  }\n"];
        [script appendString:@"})();\n\n"];
        */

        // Set cookies in a direct called function. This ensures that no
        // javascript error will break the web content javascript.
          // Generates JS: document.cookie = "key=value; Path=/; Expires=Thu, 01 Jan 20xx 00:00:01 GMT;"
        // for each cookie which is available in the application context.
        [script appendString:@"(function () {\n"];
        for (NSHTTPCookie *cookie in [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookies]) {
          [script appendFormat:@"document.cookie = %@ + '=' + %@",
            RCTJSONStringify(cookie.name, NULL),
            RCTJSONStringify(cookie.value, NULL)];
          if (cookie.path) {
            [script appendFormat:@" + '; Path=' + %@", RCTJSONStringify(cookie.path, NULL)];
          }
          if (cookie.expiresDate) {
            [script appendFormat:@" + '; Expires=' + new Date(%f).toUTCString()",
              cookie.expiresDate.timeIntervalSince1970 * 1000
            ];
          }
          [script appendString:@";\n"];
        }
        [script appendString:@"})();\n"];

        WKUserScript* cookieInScript = [[WKUserScript alloc] initWithSource:script
                                                              injectionTime:WKUserScriptInjectionTimeAtDocumentStart
                                                           forMainFrameOnly:YES];
        [wkWebViewConfig.userContentController addUserScript:cookieInScript];
      }
    }

    _webView = [[WKWebView alloc] initWithFrame:self.bounds configuration: wkWebViewConfig];
    _webView.scrollView.delegate = self;
    _webView.UIDelegate = self;
    _webView.navigationDelegate = self;
    _webView.scrollView.scrollEnabled = _scrollEnabled;
    _webView.scrollView.pagingEnabled = _pagingEnabled;
    _webView.scrollView.bounces = _bounces;
    _webView.scrollView.showsHorizontalScrollIndicator = _showsHorizontalScrollIndicator;
    _webView.scrollView.showsVerticalScrollIndicator = _showsVerticalScrollIndicator;
    _webView.scrollView.directionalLockEnabled = _directionalLockEnabled;
    _webView.allowsLinkPreview = _allowsLinkPreview;
    [_webView addObserver:self forKeyPath:@"estimatedProgress" options:NSKeyValueObservingOptionOld | NSKeyValueObservingOptionNew context:nil];
    _webView.allowsBackForwardNavigationGestures = _allowsBackForwardNavigationGestures;

    if (_userAgent) {
      _webView.customUserAgent = _userAgent;
    }
#if defined(__IPHONE_OS_VERSION_MAX_ALLOWED) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 110000 /* __IPHONE_11_0 */
    if ([_webView.scrollView respondsToSelector:@selector(setContentInsetAdjustmentBehavior:)]) {
      _webView.scrollView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
    }
#endif

    [self addSubview:_webView];
    [self setHideKeyboardAccessoryView: _savedHideKeyboardAccessoryView];
    [self setKeyboardDisplayRequiresUserAction: _savedKeyboardDisplayRequiresUserAction];
    [self visitSource];
  }
}

// Update webview property when the component prop changes.
- (void)setAllowsBackForwardNavigationGestures:(BOOL)allowsBackForwardNavigationGestures {
  _allowsBackForwardNavigationGestures = allowsBackForwardNavigationGestures;
  _webView.allowsBackForwardNavigationGestures = _allowsBackForwardNavigationGestures;
}


- (void)removeFromSuperview
{
    if (_webView) {
        [_webView.configuration.userContentController removeScriptMessageHandlerForName:MessageHandlerName];
        [_webView removeObserver:self forKeyPath:@"estimatedProgress"];
        [_webView removeFromSuperview];
        _webView.scrollView.delegate = nil;
        _webView = nil;
    }

    [super removeFromSuperview];
}

-(void)keyboardWillHide
{
    keyboardTimer = [NSTimer scheduledTimerWithTimeInterval:0 target:self selector:@selector(keyboardDisplacementFix) userInfo:nil repeats:false];
    [[NSRunLoop mainRunLoop] addTimer:keyboardTimer forMode:NSRunLoopCommonModes];
}
-(void)keyboardWillShow
{
    if (keyboardTimer != nil) {
        [keyboardTimer invalidate];
    }
}
-(void)keyboardDisplacementFix
{
    // Additional viewport checks to prevent unintentional scrolls
    UIScrollView *scrollView = self.webView.scrollView;
    double maxContentOffset = scrollView.contentSize.height - scrollView.frame.size.height;
    if (maxContentOffset < 0) {
        maxContentOffset = 0;
    }
    if (scrollView.contentOffset.y > maxContentOffset) {
      // https://stackoverflow.com/a/9637807/824966
      [UIView animateWithDuration:.25 animations:^{
          scrollView.contentOffset = CGPointMake(0, maxContentOffset);
      }];
    }
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{
    if ([keyPath isEqual:@"estimatedProgress"] && object == self.webView) {
        if(_onLoadingProgress){
             NSMutableDictionary<NSString *, id> *event = [self baseEvent];
            [event addEntriesFromDictionary:@{@"progress":[NSNumber numberWithDouble:self.webView.estimatedProgress]}];
            _onLoadingProgress(event);
        }
    }else{
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}

- (void)setBackgroundColor:(UIColor *)backgroundColor
{
  _savedBackgroundColor = backgroundColor;
  if (_webView == nil) {
    return;
  }

  CGFloat alpha = CGColorGetAlpha(backgroundColor.CGColor);
  self.opaque = _webView.opaque = (alpha == 1.0);
  _webView.scrollView.backgroundColor = backgroundColor;
  _webView.backgroundColor = backgroundColor;
}

/**
 * This method is called whenever JavaScript running within the web view calls:
 *   - window.webkit.messageHandlers[MessageHandlerName].postMessage
 */
- (void)userContentController:(WKUserContentController *)userContentController
       didReceiveScriptMessage:(WKScriptMessage *)message
{
  if (_onMessage != nil) {
    NSMutableDictionary<NSString *, id> *event = [self baseEvent];
    [event addEntriesFromDictionary: @{@"data": message.body}];
    _onMessage(event);
  }
}

- (void)setSource:(NSDictionary *)source
{
  if (![_source isEqualToDictionary:source]) {
    _source = [source copy];

    if (_webView != nil) {
      [self visitSource];
    }
  }
}

- (void)setContentInset:(UIEdgeInsets)contentInset
{
  _contentInset = contentInset;
  [RCTView autoAdjustInsetsForView:self
                    withScrollView:_webView.scrollView
                      updateOffset:NO];
}

- (void)refreshContentInset
{
  [RCTView autoAdjustInsetsForView:self
                    withScrollView:_webView.scrollView
                      updateOffset:YES];
}

- (void)visitSource
{
    // Check for a static html source first
    NSString *html = [RCTConvert NSString:_source[@"html"]];
    if (html) {
        NSURL *baseURL = [RCTConvert NSURL:_source[@"baseUrl"]];
        if (!baseURL) {
            baseURL = [NSURL URLWithString:@"about:blank"];
        }
        [_webView loadHTMLString:html baseURL:baseURL];
        return;
    }

    NSURLRequest *request = [self requestForSource:_source];
    // Because of the way React works, as pages redirect, we actually end up
    // passing the redirect urls back here, so we ignore them if trying to load
    // the same url. We'll expose a call to 'reload' to allow a user to load
    // the existing page.
    if ([request.URL isEqual:_webView.URL]) {
        return;
    }
    if (!request.URL) {
        // Clear the webview
        [_webView loadHTMLString:@"" baseURL:nil];
        return;
    }
    if (request.URL.host) {
        [_webView loadRequest:request];
    }
    else {
        [_webView loadFileURL:request.URL allowingReadAccessToURL:request.URL];
    }
}

-(void)setKeyboardDisplayRequiresUserAction:(BOOL)keyboardDisplayRequiresUserAction
{
    if (_webView == nil) {
        _savedKeyboardDisplayRequiresUserAction = keyboardDisplayRequiresUserAction;
        return;
    }
  
    if (_savedKeyboardDisplayRequiresUserAction == true) {
        return;
    }
  
    UIView* subview;
  
    for (UIView* view in _webView.scrollView.subviews) {
        if([[view.class description] hasPrefix:@"WK"])
            subview = view;
    }
  
    if(subview == nil) return;
  
    Class class = subview.class;
  
    NSOperatingSystemVersion iOS_11_3_0 = (NSOperatingSystemVersion){11, 3, 0};
    NSOperatingSystemVersion iOS_12_2_0 = (NSOperatingSystemVersion){12, 2, 0};

    Method method;
    IMP override;
  
    if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion: iOS_12_2_0]) {
        // iOS 12.2.0 - Future
        SEL selector = sel_getUid("_elementDidFocus:userIsInteracting:blurPreviousNode:changingActivityState:userObject:");
        method = class_getInstanceMethod(class, selector);
        IMP original = method_getImplementation(method);
        override = imp_implementationWithBlock(^void(id me, void* arg0, BOOL arg1, BOOL arg2, BOOL arg3, id arg4) {
            ((void (*)(id, SEL, void*, BOOL, BOOL, BOOL, id))original)(me, selector, arg0, TRUE, arg2, arg3, arg4);
        });
    }
    else if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion: iOS_11_3_0]) {
        // iOS 11.3.0 - 12.2.0
        SEL selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:changingActivityState:userObject:");
        method = class_getInstanceMethod(class, selector);
        IMP original = method_getImplementation(method);
        override = imp_implementationWithBlock(^void(id me, void* arg0, BOOL arg1, BOOL arg2, BOOL arg3, id arg4) {
            ((void (*)(id, SEL, void*, BOOL, BOOL, BOOL, id))original)(me, selector, arg0, TRUE, arg2, arg3, arg4);
        });
    } else {
        // iOS 9.0 - 11.3.0
        SEL selector = sel_getUid("_startAssistingNode:userIsInteracting:blurPreviousNode:userObject:");
        method = class_getInstanceMethod(class, selector);
        IMP original = method_getImplementation(method);
        override = imp_implementationWithBlock(^void(id me, void* arg0, BOOL arg1, BOOL arg2, id arg3) {
            ((void (*)(id, SEL, void*, BOOL, BOOL, id))original)(me, selector, arg0, TRUE, arg2, arg3);
        });
    }
  
    method_setImplementation(method, override);
}

-(void)setHideKeyboardAccessoryView:(BOOL)hideKeyboardAccessoryView
{
    if (_webView == nil) {
        _savedHideKeyboardAccessoryView = hideKeyboardAccessoryView;
        return;
    }

    if (_savedHideKeyboardAccessoryView == false) {
        return;
    }

    UIView* subview;

    for (UIView* view in _webView.scrollView.subviews) {
        if([[view.class description] hasPrefix:@"WK"])
            subview = view;
    }

    if(subview == nil) return;

    NSString* name = [NSString stringWithFormat:@"%@_SwizzleHelperWK", subview.class.superclass];
    Class newClass = NSClassFromString(name);

    if(newClass == nil)
    {
        newClass = objc_allocateClassPair(subview.class, [name cStringUsingEncoding:NSASCIIStringEncoding], 0);
        if(!newClass) return;

        Method method = class_getInstanceMethod([_SwizzleHelperWK class], @selector(inputAccessoryView));
        class_addMethod(newClass, @selector(inputAccessoryView), method_getImplementation(method), method_getTypeEncoding(method));

        objc_registerClassPair(newClass);
    }

    object_setClass(subview, newClass);
}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
  scrollView.decelerationRate = _decelerationRate;
}

- (void)setScrollEnabled:(BOOL)scrollEnabled
{
  _scrollEnabled = scrollEnabled;
  _webView.scrollView.scrollEnabled = scrollEnabled;
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
  // Don't allow scrolling the scrollView.
  if (!_scrollEnabled) {
    scrollView.bounds = _webView.bounds;
  }
}

- (void)setDirectionalLockEnabled:(BOOL)directionalLockEnabled
{
    _directionalLockEnabled = directionalLockEnabled;
    _webView.scrollView.directionalLockEnabled = directionalLockEnabled;
}

- (void)setShowsHorizontalScrollIndicator:(BOOL)showsHorizontalScrollIndicator
{
    _showsHorizontalScrollIndicator = showsHorizontalScrollIndicator;
    _webView.scrollView.showsHorizontalScrollIndicator = showsHorizontalScrollIndicator;
}

- (void)setShowsVerticalScrollIndicator:(BOOL)showsVerticalScrollIndicator
{
    _showsVerticalScrollIndicator = showsVerticalScrollIndicator;
    _webView.scrollView.showsVerticalScrollIndicator = showsVerticalScrollIndicator;
}

- (void)postMessage:(NSString *)message
{
  NSDictionary *eventInitDict = @{@"data": message};
  NSString *source = [NSString
    stringWithFormat:@"window.dispatchEvent(new MessageEvent('message', %@));",
    RCTJSONStringify(eventInitDict, NULL)
  ];
  [self injectJavaScript: source];
}

- (void)layoutSubviews
{
  [super layoutSubviews];

  // Ensure webview takes the position and dimensions of RNCWKWebView
  _webView.frame = self.bounds;
}

- (NSMutableDictionary<NSString *, id> *)baseEvent
{
  NSDictionary *event = @{
    @"url": _webView.URL.absoluteString ?: @"",
    @"title": _webView.title ?: @"",
    @"loading" : @(_webView.loading),
    @"canGoBack": @(_webView.canGoBack),
    @"canGoForward" : @(_webView.canGoForward)
  };
  return [[NSMutableDictionary alloc] initWithDictionary: event];
}

+ (void)setClientAuthenticationCredential:(nullable NSURLCredential*)credential {
  clientAuthenticationCredential = credential;
}

- (void)                    webView:(WKWebView *)webView
  didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
                  completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential * _Nullable))completionHandler
{
  if (!clientAuthenticationCredential) {
    completionHandler(NSURLSessionAuthChallengePerformDefaultHandling, nil);
    return;
  }
  if ([[challenge protectionSpace] authenticationMethod] == NSURLAuthenticationMethodClientCertificate) {
    completionHandler(NSURLSessionAuthChallengeUseCredential, clientAuthenticationCredential);
  } else {
    completionHandler(NSURLSessionAuthChallengePerformDefaultHandling, nil);
  }
}

#pragma mark - WKNavigationDelegate methods

/**
* alert
*/
- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler
{
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"" message:message preferredStyle:UIAlertControllerStyleAlert];
    [alert addAction:[UIAlertAction actionWithTitle:@"Ok" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        completionHandler();
    }]];
    [[self topViewController] presentViewController:alert animated:YES completion:NULL];

}

/**
* confirm
*/
- (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL))completionHandler{
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"" message:message preferredStyle:UIAlertControllerStyleAlert];
    [alert addAction:[UIAlertAction actionWithTitle:@"Ok" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        completionHandler(YES);
    }]];
    [alert addAction:[UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
        completionHandler(NO);
    }]];
    [[self topViewController] presentViewController:alert animated:YES completion:NULL];
}

/**
* prompt
*/
- (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString *))completionHandler{
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"" message:prompt preferredStyle:UIAlertControllerStyleAlert];
    [alert addTextFieldWithConfigurationHandler:^(UITextField *textField) {
        textField.textColor = [UIColor lightGrayColor];
        textField.placeholder = defaultText;
    }];
    [alert addAction:[UIAlertAction actionWithTitle:@"Ok" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        completionHandler([[alert.textFields lastObject] text]);
    }]];
    [[self topViewController] presentViewController:alert animated:YES completion:NULL];
}

/**
 * topViewController
 */
-(UIViewController *)topViewController{
   UIViewController *controller = [self topViewControllerWithRootViewController:[self getCurrentWindow].rootViewController];
   return controller;
}

/**
 * topViewControllerWithRootViewController
 */
-(UIViewController *)topViewControllerWithRootViewController:(UIViewController *)viewController{
  if (viewController==nil) return nil;
  if (viewController.presentedViewController!=nil) {
    return [self topViewControllerWithRootViewController:viewController.presentedViewController];
  } else if ([viewController isKindOfClass:[UITabBarController class]]){
    return [self topViewControllerWithRootViewController:[(UITabBarController *)viewController selectedViewController]];
  } else if ([viewController isKindOfClass:[UINavigationController class]]){
    return [self topViewControllerWithRootViewController:[(UINavigationController *)viewController visibleViewController]];
  } else {
    return viewController;
  }
}
/**
 * getCurrentWindow
 */
-(UIWindow *)getCurrentWindow{
  UIWindow *window = [UIApplication sharedApplication].keyWindow;
  if (window.windowLevel!=UIWindowLevelNormal) {
    for (UIWindow *wid in [UIApplication sharedApplication].windows) {
      if (window.windowLevel==UIWindowLevelNormal) {
        window = wid;
        break;
      }
    }
  }
  return window;
}


/**
 * Decides whether to allow or cancel a navigation.
 * @see https://fburl.com/42r9fxob
 */
- (void)                  webView:(WKWebView *)webView
  decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction
                  decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler
{
  static NSDictionary<NSNumber *, NSString *> *navigationTypes;
  static dispatch_once_t onceToken;

  dispatch_once(&onceToken, ^{
    navigationTypes = @{
      @(WKNavigationTypeLinkActivated): @"click",
      @(WKNavigationTypeFormSubmitted): @"formsubmit",
      @(WKNavigationTypeBackForward): @"backforward",
      @(WKNavigationTypeReload): @"reload",
      @(WKNavigationTypeFormResubmitted): @"formresubmit",
      @(WKNavigationTypeOther): @"other",
    };
  });

  WKNavigationType navigationType = navigationAction.navigationType;
  NSURLRequest *request = navigationAction.request;

  if (_onShouldStartLoadWithRequest) {
    NSMutableDictionary<NSString *, id> *event = [self baseEvent];
    [event addEntriesFromDictionary: @{
      @"url": (request.URL).absoluteString,
      @"navigationType": navigationTypes[@(navigationType)]
    }];
    if (![self.delegate webView:self
      shouldStartLoadForRequest:event
                   withCallback:_onShouldStartLoadWithRequest]) {
      decisionHandler(WKNavigationResponsePolicyCancel);
      return;
    }
  }

  if (_onLoadingStart) {
    // We have this check to filter out iframe requests and whatnot
    BOOL isTopFrame = [request.URL isEqual:request.mainDocumentURL];
    if (isTopFrame) {
      NSMutableDictionary<NSString *, id> *event = [self baseEvent];
      [event addEntriesFromDictionary: @{
        @"url": (request.URL).absoluteString,
        @"navigationType": navigationTypes[@(navigationType)]
      }];
      _onLoadingStart(event);
    }
  }

  // Allow all navigation by default
  decisionHandler(WKNavigationResponsePolicyAllow);
}

/**
 * Called when an error occurs while the web view is loading content.
 * @see https://fburl.com/km6vqenw
 */
- (void)               webView:(WKWebView *)webView
  didFailProvisionalNavigation:(WKNavigation *)navigation
                     withError:(NSError *)error
{
  if (_onLoadingError) {
    if ([error.domain isEqualToString:NSURLErrorDomain] && error.code == NSURLErrorCancelled) {
      // NSURLErrorCancelled is reported when a page has a redirect OR if you load
      // a new URL in the WebView before the previous one came back. We can just
      // ignore these since they aren't real errors.
      // http://stackoverflow.com/questions/1024748/how-do-i-fix-nsurlerrordomain-error-999-in-iphone-3-0-os
      return;
    }

    if ([error.domain isEqualToString:@"WebKitErrorDomain"] && error.code == 102) {
      // Error code 102 "Frame load interrupted" is raised by the WKWebView
      // when the URL is from an http redirect. This is a common pattern when
      // implementing OAuth with a WebView.
      return;
    }

    NSMutableDictionary<NSString *, id> *event = [self baseEvent];
    [event addEntriesFromDictionary:@{
      @"didFailProvisionalNavigation": @YES,
      @"domain": error.domain,
      @"code": @(error.code),
      @"description": error.localizedDescription,
    }];
    _onLoadingError(event);
  }

  [self setBackgroundColor: _savedBackgroundColor];
}

- (void)evaluateJS:(NSString *)js
          thenCall: (void (^)(NSString*)) callback
{
  [self.webView evaluateJavaScript: js completionHandler: ^(id result, NSError *error) {
    if (error == nil) {
      if (callback != nil) {
        callback([NSString stringWithFormat:@"%@", result]);
      }
    } else {
      RCTLogError(@"Error evaluating injectedJavaScript: This is possibly due to an unsupported return type. Try adding true to the end of your injectedJavaScript string.");
    }
  }];
}

/**
 * Called when the navigation is complete.
 * @see https://fburl.com/rtys6jlb
 */
- (void)      webView:(WKWebView *)webView
  didFinishNavigation:(WKNavigation *)navigation
{
  if (_injectedJavaScript) {
    [self evaluateJS: _injectedJavaScript thenCall: ^(NSString *jsEvaluationValue) {
      NSMutableDictionary *event = [self baseEvent];
      event[@"jsEvaluationValue"] = jsEvaluationValue;

      if (self.onLoadingFinish) {
        self.onLoadingFinish(event);
      }
    }];
  } else if (_onLoadingFinish) {
    _onLoadingFinish([self baseEvent]);
  }

  [self setBackgroundColor: _savedBackgroundColor];
}

- (void)injectJavaScript:(NSString *)script
{
  [self evaluateJS: script thenCall: nil];
}

- (void)goForward
{
  [_webView goForward];
}

- (void)goBack
{
  [_webView goBack];
}

- (void)reload
{
  /**
   * When the initial load fails due to network connectivity issues,
   * [_webView reload] doesn't reload the webpage. Therefore, we must
   * manually call [_webView loadRequest:request].
   */
  NSURLRequest *request = [self requestForSource:self.source];

  if (request.URL && !_webView.URL.absoluteString.length) {
    [_webView loadRequest:request];
  } else {
    [_webView reload];
  }
}

- (void)stopLoading
{
  [_webView stopLoading];
}

- (void)setBounces:(BOOL)bounces
{
  _bounces = bounces;
  _webView.scrollView.bounces = bounces;
}

- (NSURLRequest *)requestForSource:(id)json {
  NSURLRequest *request = [RCTConvert NSURLRequest:self.source];

  // If sharedCookiesEnabled we automatically add all application cookies to the
  // http request. This is automatically done on iOS 11+ in the WebView constructor.
  // Se we need to manually add these shared cookies here only for iOS versions < 11.
  if (_sharedCookiesEnabled) {
    if (@available(iOS 11.0, *)) {
      // see WKWebView initialization for added cookies
    } else {
      NSArray *cookies = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookiesForURL:request.URL];
      NSDictionary<NSString *, NSString *> *cookieHeader = [NSHTTPCookie requestHeaderFieldsWithCookies:cookies];
      NSMutableURLRequest *mutableRequest = [request mutableCopy];
      [mutableRequest setAllHTTPHeaderFields:cookieHeader];
      return mutableRequest;
    }
  }
  return request;
}

@end