WebKit 获取元素 URL？ iOS8

Question

我正在制作一个使用 WKWebView 的应用程序，我需要能够获取页面上任何 HTML 元素的 URL。例如，假设用户访问谷歌图像并长按图像，我需要能够找到该图像的完整 URL。

有人知道怎么做吗？

谢谢！

Answer 1

此行为可以通过以下 4 个步骤来完成：

1) 将UILongPressGestureRecognizer 添加到您的WKWebView 实例中，不要忘记让您的识别器与自己的WKWebView 手势识别器同时识别：

SEL selector = @selector(handleLongPressGestureRecognizer:);
UILongPressGestureRecognizer* gestuRecognizer =
    [[UILongPressGestureRecognizer alloc] initWithTarget:self
                                                        action:selector];
gestuRecognizer.delegate = self;
[webView addGestureRecognizer:gestuRecognizer];

<...>

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

2) 大致如下创建 JavaScript 文件(tools.js)：

function imageSourceFromPoint(x, y) {
  var element = document.elementFromPoint(x, y);
  if (element.tagName == 'IMG' && element.src) {
    return element.src;
  }
  return null;
}

3) 将该 tools.js 加载到您的网页中。这可以直接在handleLongPressGestureRecognizer 方法中完成，例如：

- (void)handleLongPressGestureRecognizer:
    (UILongPressGestureRecognizer*)recognizer {
  if (recognizer.state == UIGestureRecognizerStateBegan) {
    [self loadJavaScriptFileIfNeededWithCompletion:^{
      <...>
    }];
  }
}

- (void)loadJavaScriptFileIfNeededWithCompletion:(void(^)())completion {
  <...>
  [self.webView evaluateJavaScript:[self toolsJavaScriptFile]
                 completionHandler:^(id result, NSError* error) {
                   completion();
                 }];
  <...>
}

- (NSString*)toolsJavaScriptFile {
  NSString* path = [[NSBundle mainBundle] pathForResource:@"tools"
                                                   ofType:@"js"];
  return [NSString stringWithContentsOfFile:path
                                   encoding:NSUTF8StringEncoding
                                      error:nil];
}

4) 从Objective-C（或Swift）执行imageSourceFromPoint JavaScript 函数，并带有长按手势的位置：

- (void)handleLongPressGestureRecognizer:
    (UILongPressGestureRecognizer*)recognizer {
    <...>
    [self loadJavaScriptFileIfNeededWithCompletion:^{
      CGPoint touchPoint = [recognizer locationInView:self.webView];
      [self imageSourceFromPoint:touchPoint completion:^(NSString* source) {
        <...>
      }];
    }];
    <...>
}

- (void)imageSourceFromPoint:(CGPoint)point
                  completion:(void(^)(NSString*))completion {
  NSString* jsCode = [NSString stringWithFormat:
      @"imageSourceFromPoint(%g, %g)", point.x, point.y];
  [self.webView evaluateJavaScript:jsCode
                 completionHandler:^(id result, NSError* error) {
                   <...>
                   NSString* resultString = (NSString*)result;
                   completion(resultString);
                 }];
}

请注意，省略了一堆错误检查，您可以在此处找到完整的项目示例https://dl.dropboxusercontent.com/u/930742/so/GetHTMLElement.zip

看起来像这样：

希望对你有所帮助。