Handling touches inside UIWebview - iphone

Question

I have created a subclass of UIWebView , and have implemented the
touchesBegan, touchesMoved and touchesEnded methods.
but the webview subclass is not handling the touch events.
Is there any method to handle the touch events inside the UIWebView subclass ???

Answer 1

No subclassing needed, just add a UITapGestureRecognizer :
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(didTapMethod)];
[tap setNumberOfTapsRequired:1]; // Set your own number here
[tap setDelegate:self]; // Add the <UIGestureRecognizerDelegate> protocol
[self.myWebView addGestureRecognizer:tap];
Add the <UIGestureRecognizerDelegate> protocol in the header file, and add this method:
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES;
}

Answer 2

If all you need is to handle gestures, while leaving the rest of the UIWebView functionality intact, you can subclass UIWebView and use this strategy:
in the init method of your UIWebView subclass, add a gesture recognizer, e.g.:
UISwipeGestureRecognizer * swipeRight = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:#selector(handleSwipeGestureRightMethod)];
swipeRight.direction = UISwipeGestureRecognizerDirectionRight;
[self addGestureRecognizer:swipeRight];
swipeRight.delegate = self;
then, add this method to your class:
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{
return YES;
}
Add and handle your designated selector to the class, in this case "handleSwipeGestureRightMethod" and you are good to go...

Answer 3

You could put an UIView over your UIWebView, and overide the touchesDidBegin etc, then send them to your webview. Ex:
User touches your UIView, which provokes a
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
// Execute your code then send a touchesBegan to your webview like so:
[webView touchesBegan:touches withEvent:event];
return;
}
your UIView has to be over the webview.

Answer 4

I'm not sure if this is what you want (it's not what you asked for, but it might work depending on what your end game is), but you could instead interpret the touches in JavaScript from inside the UIWebView, and get javascript to do
document.location='http://null/'+xCoord+'/'+yCoord; // Null is arbitrary.
Then you can catch that using the UIWebView's delegate method
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
And if the request.URL.host (or whatever it is) isEqualToString:#"null" take the relevant action (and return NO instead of YES). You can even add the JS to each page by doing something like:
- (void)webViewDidFinishLoad:(UIWebView *)webView {
[webView stringByEvaluatingJavaScriptFromString:#"window.ontouchstart=function(/* ... */);"];
}
Hope this helps?

Answer 5

Handling gestures on a UIWebView is discussed in this Apple Developer forum thread.
Using the info given there, there will be no need for an extra view in most or all cases, and as mentioned here before, overriding UIWebView is not the way to go.
Copypaste of the most important post in the thread:
This is a known issue. The UIWebView has its own UITapGestureRecognizers, and they're on a private subview of the UIWebView itself. UIGestureRecognizer precedence defines that gestures attached to views deeper in the view hierarchy will exclude ones on superviews, so the web view's tap gestures will always win over yours.
If it's okay in your case to allow your tap to happen along with the web view's normal tap your best solution would be to implement the UIGestureRecognizerDelegate method gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer and return YES for other tap gestures. This way you'll get your tap handler called, and the web view will still get its called.
If you need to be the only one handling the tap you'll have to subclass UITapGestureRecognizer so you can use the one-way overrides in UIGestureRecognizerSubclass.h, an you can then return NO from canBePreventedByGestureRecognizer: when asked if the web view's tap gesture recognizer can prevent yours.
In any case, we know about this and hope to make it easier in the future.

Answer 6

I've just found that UIWebView does check whether it responds to the - (void)webViewDidNotClick: (id)webBrowserView selector, once one taps on the view area (not on hyperref, or any other area that should be handled specifically). So you may implement that selector with your handling code :)

Answer 7

Do you mean your sub-classed implementation is not called when touchesBegan, touchesMoved and touchesEnded are called?
It sounds like a problem with how you've created an instance of the object. More details are required I think.
(taken form comments)
Header File
#import <UIKit/UIKit.h>
#interface MyWebView : UIWebView { } #end
Implementation File
#import "MyWebView.h"
#implementation MyWebView
- (id)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) { } return self;
}
- (void)drawRect:(CGRect)rect {
NSLog(#"MyWebView is loaded");
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"touches began");
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"Touches ended");
}
- (void)dealloc {
[super dealloc];
}
#end

Answer 8

I would try overriding -sendEvent: on UIWindow, to see if you can intercept those touch events.

Answer 9

Following on from what Unfalkster said, you can use the hitTest method to achieve what you want, but you don't have to subclass UIWindow. Just put this in your web view subclass. You will get a compile time warning but it does work:
- (void)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
if (event.type == UIEventTypeTouches) {
// get location info
CGFloat x = point.x;
CGFloat y = point.y;
// get touches
NSSet *touches = [event allTouches];
// individual touches
for (UITouch *touch in touches) {
if (touch.phase == UITouchPhaseBegan) {
// touches began
} else if (touch.phase == UITouchPhaseMoved) {
}
// etc etc
}
}
// call the super
[super hitTest:point withEvent:event];
}
Hope that helps!

Answer 10

If you want to detect your own taps but disable the UIWebView's taps then you can use my solution:
-(void)recursivelyDisableTapsOnView:(UIView*)v{
for(UIView* view in v.subviews){
for(UIGestureRecognizer* g in view.gestureRecognizers){
if(g == self.ownTapRecognizer){
continue;
}
if([g isKindOfClass:[UITapGestureRecognizer class]] ||
[g isKindOfClass:[UILongPressGestureRecognizer class]] ||
[g isKindOfClass:NSClassFromString(#"UITapAndAHalfRecognizer")]){
g.enabled = NO;
}
}
[self recursivelyDisableTapsOnView:view];
}
}
- (void)webViewDidFinishLoad:(UIWebView *)webView{
[self recursivelyDisableTapsOnView:webView];
//disable selection
[webView stringByEvaluatingJavaScriptFromString:#"document.documentElement.style.webkitUserSelect='none';"];
// Disable callout
[webView stringByEvaluatingJavaScriptFromString:#"document.documentElement.style.webkitTouchCallout='none';"];
}