Draggable cards (touch enumeration) issue

Posted by glitch on Stack Overflow See other posts from Stack Overflow or by glitch
Published on 2009-08-08T21:13:11Z Indexed on 2010/05/28 20:01 UTC
Read the original article Hit count: 186

I'm trying to let a player tap, drag and release a card from a fanned stack on the screen to a 4x4 field on the board. My cards are instantiated from a custom class that inherits from the UIImageView class.

I started with the Touches sample app, and I modified the event handlers for touches to iterate over my player's card hand instead of the 3 squares the sample app allows you to move on screen. Everything works, until that is, I move the card I'm dragging near another card. I'm really drawing a blank here for the logic to get the cards to behave properly. Here's my code:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{
NSUInteger numTaps = [[touches anyObject] tapCount];
if(numTaps = 1) {
	for (UITouch *touch in touches) {
		[self dispatchFirstTouchAtPoint:[touch locationInView: self.boardCardView] forEvent:nil];
    	}	
    }
}

-(void) dispatchFirstTouchAtPoint:(CGPoint)touchPoint forEvent:(UIEvent *)event
{
    for (int i = 0; i<5; i++)
    {
    	UIImageView *touchedCard = boardBuffer[i];
    	if (CGRectContainsPoint([touchedCard frame], touchPoint)) {
    		[self animateFirstTouchAtPoint:touchPoint forView:touchedCard];
    	}
    }
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{  
    NSUInteger touchCount = 0;
    for (UITouch *touch in touches){
     	[self dispatchTouchEvent:[touch view] toPosition:[touch locationInView:self.boardCardView]];
        touchCount++;
    }		
}

My questions are:

  1. How do I get the touch logic to disallow other cards from being picked up by a dragging finger?

  2. Is there anyway I can only enumerate the objects that are directly below a player's finger and explicitly disable other objects from responding?

Thanks!

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