Is there a way to pass touches through on the iPhone?

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?

Solution 1:

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]; 
}

Solution 2:

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

Solution 3:

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