Javascript WKWebView自定义长按菜单工作正常，但存在一些主要问题

当用户长按链接时，警报控制器将显示以下选项：

• 打开
• 在新选项卡中打开
• 抄袭

目前存在两个问题：

如果用户在WKWebView完成导航之前长按，则会显示默认（Safari）警报控制器

如果用户在弹出动画以某种方式出现后抬起手指，WKWebView会将其注册为点击，并在屏幕上仍显示警报控制器时导航到该链接

这一机制分为三个部分

首先,

WKWebView完成导航后，将向页面注入javascript，以禁用默认警报控制器

- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation
{
    [_webView evaluateJavaScript:@"document.body.style.webkitTouchCallout='none';"
               completionHandler:^(id result, NSError *error){

                   NSLog(@"Javascript: {%@, %@}", result, error.description);
               }];
}

第二,

将UILongPressGestureRecognitor添加到WKWebView并实现，以便它根据触摸的位置查找元素的属性

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

- (void)longPress:(UILongPressGestureRecognizer *)longPressGestureRecognizer
{
    if (longPressGestureRecognizer.state == UIGestureRecognizerStateBegan) {

        _shouldCancelNavigation = YES;

        CGPoint touchLocation = [longPressGestureRecognizer locationInView:_webView];

        NSString *javascript = [NSString stringWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"Javascript" ofType:@"js"]
                                                         encoding:NSUTF8StringEncoding
                                                            error:nil];

        [_webView evaluateJavaScript:javascript
                   completionHandler:^(id result, NSError *error){

                       NSLog(@"Javascript: {%@, %@}", result, error.description);
                   }];

        [_webView evaluateJavaScript:[NSString stringWithFormat:@"MyAppGetHTMLElementsAtPoint(%f,%f);", touchLocation.x, touchLocation.y]
                   completionHandler:^(id result, NSError *error){

                       NSLog(@"Javascript: {%@, %@}", result, error.description);

                       NSString *tags = (NSString *)result;

                       if ([tags containsString:@",A,"]) {

                           [_webView evaluateJavaScript:[NSString stringWithFormat:@"MyAppGetHREFAttributeAtPoint(%f,%f);", touchLocation.x, touchLocation.y]
                                      completionHandler:^(id result, NSError *error){

                                          NSLog(@"Javascript: {%@, %@}", result, error.description);

                                          NSString *urlString = (NSString *)result;

                                          [_delegate webView:self didLongPressAtTouchLocation:touchLocation URL:[NSURL URLWithString:urlString]];
                                      }];

                           return;
                       }

                       if ([tags containsString:@",IMG,"]) {

                           [_webView evaluateJavaScript:[NSString stringWithFormat:@"MyAppGetSRCAttributeAtPoint(%f,%f);", touchLocation.x, touchLocation.y]
                                      completionHandler:^(id result, NSError *error){

                                          NSLog(@"Javascript: {%@, %@}", result, error.description);

                                          NSString *urlString = (NSString *)result;

                                          [_delegate webView:self didLongPressAtTouchLocation:touchLocation imageWithSourceURL:[NSURL URLWithString:urlString]];
                                      }];

                           return;
                       }
                   }];
    }
}

最后,

表示警报控制器的委托方法在主ViewController上实现

- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation
{
    [_webView evaluateJavaScript:@"document.body.style.webkitTouchCallout='none';"
               completionHandler:^(id result, NSError *error){

                   NSLog(@"Javascript: {%@, %@}", result, error.description);
               }];
}

我对第二个问题的解决方案是添加一个布尔值shouldCancelNavigation，该值在显示警报控制器时为YES，在解除警报控制器时为NO

- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler
{
    if (_shouldCancelNavigation) {

        decisionHandler(WKNavigationActionPolicyCancel);
    }
    else {

        decisionHandler(WKNavigationActionPolicyAllow);
    }
}

有趣的是，网上有很多链接不需要决策的例子。他们只是发生了，我没有办法阻止他们

例如：

资料来源：

资料来源2：

编辑：

这解决了第二个问题，但我不确定它是否会在其他地方损坏某些东西

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    if ([otherGestureRecognizer isKindOfClass:[UILongPressGestureRecognizer class]]) {

        otherGestureRecognizer.enabled = NO;

        otherGestureRecognizer.enabled = YES;
    }

    return YES;
}

编辑2：

它确实造成了一个问题。。。您不能再选择文本，因为上面的代码会重置内部长按手势识别器

编辑3：

如果我完全删除我的实现（全部3个步骤），并让默认警报控制器在每次我长按链接时启动，第二个问题就会得到解决

---

苹果的alert控制器有一点在你抬起手指后会阻止WKWebView导航。

如果我没说错的话，在第二部分：

- (void)longPress:(UILongPressGestureRecognizer *)longPressGestureRecognizer
{
    if (longPressGestureRecognizer.state == UIGestureRecognizerStateBegan) {

//Rest of your code ...
    }
}

您正在注入javascript以禁用系统对话框。现在，在新闻结束后，WKWebview已经收到从web链接触发的事件。既然为时已晚，为什么不尝试检查

LongPressGestureRecognitzer的条件。状态

等于

UIGestureRecognitzerStateEnded

因此它改为下面的代码

    if (longPressGestureRecognizer.state == UIGestureRecognizerStateEnded) {

       //Rest of your code ...
    }

---

我还没有测试这段代码。如果它能工作，我会更高兴。

这个答案可以解决第二个问题，但我不确定它对App Store是否安全。

首先，您需要断开内部长按手势识别器，以便在用户抬起手指时它们不会触发

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    if ([otherGestureRecognizer isKindOfClass:[UILongPressGestureRecognizer class]]) {

        if (otherGestureRecognizer.state == UIGestureRecognizerStateBegan) {

            // Warning: This will break how WKWebView handles selection of text.

            [otherGestureRecognizer requireGestureRecognizerToFail:gestureRecognizer];
        }
    }

    return YES;
}

用户完成与自定义长按菜单的交互后，此代码将修复损坏的WKWebView：

    [_webView removeGestureRecognizer:_longPressGestureRecognizer]; // This code will remove the dependency and recover the lost functionality.

    _longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];

    _longPressGestureRecognizer.numberOfTouchesRequired = 1;

    _longPressGestureRecognizer.delegate = self;

    [_webView addGestureRecognizer:_longPressGestureRecognizer];

---

这就是一种黑客行为。

我在页面加载完成时注入javascript以禁用系统对话框，而不是在手势识别器阶段开始时。而且，这是问题的第一部分。