检测UIWebView内的水龙头

Question

我有一个UIWebView导航栏和工具栏,我想自动隐藏.我已经这样做了,但我想在用户点击时显示它们UIWebView.

我的问题是UIWebView捕获所有触摸事件,我无法拦截我需要的那个.

这有什么解决方法吗？

Answer 1

来自Mithin Kumar的博客文章(不加载,但谢天谢地,它是谷歌缓存).

(Mithin,我希望你不介意我把它转发到这里;如果你这样做,请在评论中告诉我,我会将其删除.)

最近,我正在开发一个需要在UIWebView上检测tap和事件的项目.我们想要找出用户在UIWebView中点击的HTML元素,然后根据点击的元素执行一些操作.经过一些谷歌搜索,我发现大多数用户在UIWebView上面放置一个透明的UIView,重新实现UIResponder类的触摸方法(例如:-touchesBegan:withEvent :),然后将事件传递给UIWebView.这里详细解释了这种方法.该方法存在多个问题.

1. 复制/选择停止在UIWebView上工作
2. 我们需要创建UIWebView的子类,而Apple说我们不应该对它进行子类化.
3. 许多其他UIWebView功能停止工作.

我们最终发现实现这一点的正确方法是通过对UIWindow进行子类化并重新实现-sendEvent:方法.这是你如何做到的.首先,创建一个UIWindow子类

#import <UIKit/UIKit.h>
@protocol TapDetectingWindowDelegate
- (void)userDidTapWebView:(id)tapPoint;
@end
@interface TapDetectingWindow : UIWindow {
    UIView *viewToObserve;
    id <TapDetectingWindowDelegate> controllerThatObserves;
}
@property (nonatomic, retain) UIView *viewToObserve;
@property (nonatomic, assign) id <TapDetectingWindowDelegate> controllerThatObserves;
@end

请注意,我们有变量告诉我们检测事件的UIView和接收事件信息的控制器.现在,按以下方式实现此类

#import "TapDetectingWindow.h"
@implementation TapDetectingWindow
@synthesize viewToObserve;
@synthesize controllerThatObserves;
- (id)initWithViewToObserver:(UIView *)view andDelegate:(id)delegate {
    if(self == [super init]) {
        self.viewToObserve = view;
        self.controllerThatObserves = delegate;
    }
    return self;
}
- (void)dealloc {
    [viewToObserve release];
    [super dealloc];
}
- (void)forwardTap:(id)touch {
    [controllerThatObserves userDidTapWebView:touch];
}
- (void)sendEvent:(UIEvent *)event {
    [super sendEvent:event];
    if (viewToObserve == nil || controllerThatObserves == nil)
        return;
    NSSet *touches = [event allTouches];
    if (touches.count != 1)
        return;
    UITouch *touch = touches.anyObject;
    if (touch.phase != UITouchPhaseEnded)
        return;
    if ([touch.view isDescendantOfView:viewToObserve] == NO)
        return;
    CGPoint tapPoint = [touch locationInView:viewToObserve];
    NSLog(@"TapPoint = %f, %f", tapPoint.x, tapPoint.y);
    NSArray *pointArray = [NSArray arrayWithObjects:[NSString stringWithFormat:@"%f", tapPoint.x],
    [NSString stringWithFormat:@"%f", tapPoint.y], nil];
    if (touch.tapCount == 1) {
        [self performSelector:@selector(forwardTap :)  withObject:pointArray afterDelay:0.5];
    }
    else if (touch.tapCount > 1) {
        [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(forwardTap :)  object:pointArray];
    }
}
@end

以上述方式实现sendEvent方法,然后您可以将所需信息发送回控制器.

人们需要记住的事情很少.确保在MainWindow.xib文件中,窗口的类型为TapDetectingWindow,而不是UIWindow.只有这样,所有事件才会通过上面重新实现的sendEvent方法.另外,请确保先调用[super sendEvent:event],然后执行任何操作.

现在,您可以通过以下方式在控制器类中创建UIWebView

@interface WebViewController : UIViewController<TapDetectingWindowDelegate> {
    IBOutlet UIWebView *mHtmlViewer; 
    TapDetectingWindow *mWindow;
}
- (void)viewDidLoad {
    [super viewDidLoad];
    mWindow = (TapDetectingWindow *)[[UIApplication sharedApplication].windows objectAtIndex:0];
    mWindow.viewToObserve = mHtmlViewer;
    mWindow.controllerThatObserves = self;
}

请记住,您需要在控制器类中编写userDidTapWebView方法.这是为了将事件信息发送到控制器类而调用的方法.在我们的上面的例子中,我们在UIWebView中发送用户点击的点.

Answer 2

您可以非常简单地使用UITapGestureRecognizer来检测UIWebView上的轻击手势.您必须实现UIGestureRecognizerDelegate方法以允许同时识别.

- (void)viewDidLoad{
    [super viewDidLoad];

    UITapGestureRecognizer *targetGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTap:)];
    targetGesture.numberOfTapsRequired = 2;
    targetGesture.delegate = self;
    [self.webView addGestureRecognizer:targetGesture];

}

// called when the recognition of one of gestureRecognizer or otherGestureRecognizer would be blocked by the other
// return YES to allow both to recognize simultaneously. the default implementation returns NO (by default no two gestures can be recognized simultaneously)
//
// note: returning YES is guaranteed to allow simultaneous recognition. returning NO is not guaranteed to prevent simultaneous recognition, as the other gesture's delegate may return YES
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{
    NSLog(@"%@", otherGestureRecognizer);
    //if you would like to manipulate the otherGestureRecognizer here is an example of how to cancel and disable it
    if([otherGestureRecognizer isKindOfClass:[UITapGestureRecognizer class]]){

        UITapGestureRecognizer *tapRecognizer = (UITapGestureRecognizer*)otherGestureRecognizer;
        if(tapRecognizer.numberOfTapsRequired == 2 && tapRecognizer.numberOfTouchesRequired == 1){

            //this disalbes and cancels all other singleTouchDoubleTap recognizers
            // default is YES. disabled gesture recognizers will not receive touches. when changed to NO the gesture recognizer will be cancelled if it's currently recognizing a gesture
            otherGestureRecognizer.enabled = NO;

        }

    }

    return YES;

}

-(void)handleTap:(id)sender{



}

Answer 3

大多数方法处理一对复杂的子类UIView和UIWebView重写-touchesBegan:withEvent:等方法。

这种基于 JavaScript 的方法拦截对 Web DOM 本身的接触，这似乎是回避更复杂过程的聪明方法。我自己还没有尝试过，但如果你尝试一下，我很想知道结果。