I have several UIButtons which I use to set the current action when tapping in the main area. I would also like to allow the user to drag from the button directly into the main area and take the same action; essentially, the touchesBegan and touchesMoved should be passed on to the main view when touching the UIButtons, but also should send the button press action.
Right now, I have the touch up inside changing the control. The drag exit calls the touch up inside section to set the control, then calls the touches began section to start the main area touching operation.
However, at this point, the touchesMoved and touchesEnded are obviously not being called, because the touches originated on the UIButton.
Is there a way to half-ignore the touches so they're passed to the main area, but also allow me to set the control first?
I know this question is two years old (and already answered), but nevertheless...
When I tried this myself, the touches were forwarded, but the buttons no longer behaved like buttons. I also passed the touches along to "super" and now all is well.
So, for beginners that might stumble upon this, this is what the code should look like:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
[self.nextResponder touchesBegan:touches withEvent:event];
}
In the documentation, look for Responder Objects and the Responder Chain
You can "share" touches between objects by forwarding the touch up the responder chain.
Your UIButton has a responder/controller that receives the UITouch events, my guess is that once it has preformed its interpretation of the message it returns - the touch has been handled and disposed of.
Apple suggests something like this (based on the type of touch of course):
[self.nextResponder touchesBegan:touches withEvent:event];
Rather than disposing of the touch event it is passed on.
Sub classed UIButton:
MyButton.h
#import <Foundation/Foundation.h>
#interface MyButton : UIButton {
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event ;
#end
MyButton.m
#import "MyButton.h"
#implementation MyButton
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
printf("MyButton touch Began\n");
[self.nextResponder touchesBegan:touches withEvent:event];
}
#end
No need to subclass either! Simply stick this on the top of your implementation before anything else:
#pragma mark PassTouch
#interface UIButton (PassTouch)
#end
#implementation UIButton (PassTouch)
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesBegan:touches withEvent:event];
[self.nextResponder touchesBegan:touches withEvent:event];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesMoved:touches withEvent:event];
[self.nextResponder touchesMoved:touches withEvent:event];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesEnded:touches withEvent:event];
[self.nextResponder touchesEnded:touches withEvent:event];
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesCancelled:touches withEvent:event];
[self.nextResponder touchesCancelled:touches withEvent:event];
}
#end
Related
I am working as a developer for the iPhone applications, but i m stuck at certain point, can anyone tell me that how do i handle the events of C or C++ in Xcode 3.2 for the iPhone development?
If you want to handle events for a UIView or any class which is subclassed from UIResponder... Just overhide touch points and handle events there...
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesBegan:touches withEvent:event];
}
-(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesEnded withEvent:event];
}
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesMoved withEvent:event];
}
Cell doesn't receive touch events, when there is UIScrollView inside UITableViewCell. Is there any way to cancel tap events for UIScrollView (needs only to handle scrolling)?
If you need touches to go through, implement a subclass of UIScrollView, and add these:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
// Pass to parent
[super touchesBegan:touches withEvent:event];
[self.nextResponder touchesBegan:touches withEvent:event];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
// Pass to parent
[super touchesEnded:touches withEvent:event];
[self.nextResponder touchesEnded:touches withEvent:event];
}
The cell only interecepts taps, so it'll work.
This is brilliant! I was pulling my hair on this one.
I've created a subclass of UIScrollView to implement a one of my custom controls, at this point everything is working great.
However what I'd like to be able to call a methods whenever a Touch Up Inside event is detected (just like interface builder) does anybody know how I could do this?
Because UIScrollView does not inherit from UIControl, this is not possible. You can, however, relay the scroll view's touch events by implementing the UIResponder methods in your custom UIScrollView class:
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
if (!self.dragging)
{
[self.nextResponder touchesEnded: touches withEvent:event];
}
[super touchesEnded: touches withEvent: event];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
if (!self.dragging)
{
[self.nextResponder touchesBegan: touches withEvent:event];
}
[super touchesBegan: touches withEvent: event];
}
I need to be able to catch touch events on a UIWebView and still be able to use the webview's contents (html links, etc...)
I have subclassed UIWebView and implemented methods:
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event;
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;
I am now able to catch touch events, but the view has become ususable :(
I then tried to set the following on the webview object in my UIViewController, but that changed nothing.
[webview setDelegate:self];
[webview setUserInteractionEnabled:YES];
Can anyone help? Do you need further info?
Tia,
S.
I ended up not subclassing UIWebView and using a Gesture Recognizer on the object in the view controller. It works really well!
S.
In each of the functions you implemented did you also call super? For instance
- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
// Your code here
[super touchesBegan:touches withEvent:event];
}
If don't call super UIWebView can't know the someone touched a link on it
I have a UIScrollView that contains a UITextView (not editable).
I can't make the UIScrollView gets the touch events, UITextView seems to get them and keep them . Any idea how to let UIScrollView gets the touch events?
I want UITextView to still be scrollable vertically (my UIScrollView is scrollable only horizontally).
In your UITextView subclass, do this:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[self.nextResponder touchesBegan:touches withEvent:event];
}
If you want UITextView to handle the touches too, then I believe you can do this:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[self.nextResponder touchesBegan:touches withEvent:event];
[super touchesBegan:touches withEvent:event];
}
but it might result in really weird behavior.