How does UIView pass Touch Events to UIViewController?

My understanding is that if you have to do touch events, you subclass the UIView, the UIViewController stays out of touch event delegation.

Say you have UIView called 'TouchView1' where u are going to track the touches.
In TouchView1 class you have the instance variable of the corresponding controller type. TouchViewController is your UIViewController.

TouchViewController *touchController;

your TouchView1 class should have either touchesMoved or touchesBegan delegate methods.

in the TouchViewController, create instance variable of type TouchView1. In the loadview method, instantiate the TouchView1 and add to your container view if you have. And set the
TouchView1.touchController =self;
Also you have the method which should be called when a touch occurs on the view. (say TouchMethod ) .


Now when you touch the TouchView1, touchesMoved and touchesBegan (correct usage of these methods depends on you) will be called and inside these method, call the function 'TouchMethod' which is in the TouchViewController .
[touchController TouchMethod];

hope it helps you...

Message was edited by: subbump

Hi,

I'm trying to integrate the method described above but I'm missing something crucial.

I have this code in my uiviewcontroller class:

- (void)loadView {

CGRect frame;

// add the top-most parent view
UIView *contentView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
contentView.backgroundColor = [UIColor blackColor];
self.view = contentView;
contentView.touchController =self;
**error: request for member 'touchController' in something not a structure or union

[contentView release];

}

- (void)touchesChangedWithEvent:(UIEvent*)event
{
NSSet *touches = [event allTouches];
for (UITouch *myTouch in touches)
{
if (myTouch.phase == UITouchPhaseBegan) {
// new touch handler
[self flipAction];
}
}

You need to subclass UIView to Myview first
with your touch handling code
(void)touchesChangedWithEvent:(UIEvent*)event

then in your viewController use this
Myview *contentView
instead of using
UIView * contentView

Hi,

After some trial and error I can get the touch event to trigger. But it can only call methods in the appdelegate class. If I try to call a method in a different file I get this runtime error:

unrecognized selector sent to class

I also get this warning when compiling:

warning: myview may not respond to mymethod
messages without a matching message signature will be assumed to return "id" and accept "..." as arguments

Doh, I just solved it.

[[myview alloc] mymethod];

sorry for the noise.

Thanks for your assistance.

The above example worked as a receiver but not as a complete solution as I was having problems getting the function called by the UIView subclass (TapView) to work properly including having issues with removeFromSuperView...

Maybe this will be helpful for saving someone else some time. Hopefully I don't get sued for breaching the NDA 🙂

In TapView.h I had to add:

@class TouchView1;

@interface TapView : UIView
{
TouchView1 * touchController;
}

@property (nonatomic, retain) TouchView1 * touchController;


in the TapView.m source file:

@synthesize touchController;


- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

[touchController TouchFunction];
}

in TouchView.h:

@class ImageTapView;

@interface TouchView1 : UIViewController {
TapView *contentView;

}

@property (nonatomic, retain) TapView *tapView;

@end

Then in the touchView1.m source file:

@synthesize tapView;

loadView{

contentView = [[ImageTapView alloc] initWithFrame:frame;
self.view = contentView;
contentView.touchController = self;

}


-(void) TouchFunction{

do something here...


}



Cheers.

I am having a related issue:
In my applicaton I want to subclass UITableViewController to create a tableview and there is a picture in one Cell, I am trying catch touch events in that cell, like move right to display next picture and move left to display previous picture.
I subclassed UITableViewCell( subclass of UIView) to create CustomCell, but I could not get the touch event. Did the CustomCell's superview get the events and not dispatch to the CustomCell?
How can I implement this? Any suggestion are highly appreciated, Thanks a lot.

For this solution of having the UIView retain the UIViewController, does this pose a problem with a retain cycle between the view and the controller?