Concurrent calls of touchesEnded

[Nunibad]

Like many others, I am trying to intercept touches within a table view. In short, I seem to be getting the event calls twice; worse, the calls are concurrent.

UITableView is subclassed, and has (among others) a method touchesEnded with code (abbreviated)

- (void)touchesEnded: (NSSet *)touches withEvent: (UIEvent *)event {
z1105++; // To count concurrency.
NSLog(@"Log 1854 touchesEnded x%x(%d):", self, z1105);
[super touchesEnded: touches withEvent: event];
NSLog(@"Log 1102 touchesEnded: after super call.");
[(AlphaTableViewController *)self.delegate touchesEnded: touches withEvent: event];
z1105--;
}

The call to super seems necessary, because without it table-cell selection doesn't work. But with it, I receive touchesEnded -twice- for the same touch, as shown by this log output:

2009-03-09 11:24:32.967 myApp [13028:20b] Log 1854 touchesEnded x52b6e0(1):
2009-03-09 11:24:32.969 myApp [13028:20b] Log 1854 touchesEnded x52b6e0(2):
2009-03-09 11:24:32.971 myApp [13028:20b] Log 1102 touchesEnded: after super call.
2009-03-09 11:24:32.971 myApp [13028:20b] Log 1102 touchesEnded: after super call.

Does anyone know why this is happening, and how to avoid it?

Thanks!

[PS -- I am aware in general terms of the fact that UIScrollView messes with hitTest, and related topics.]

[brendand]

Did you have any resolution to this? I seem to be having similar problems.

[Nunibad]

Originally Posted by brendand

Did you have any resolution to this? I seem to be having similar problems.

Not yet, Brendan. But I think I have a better idea of what might be going on. I believe the table view is over-riding hittest in order to capture the touch events before the table cell that would normally do so, in order to check whether the gesture is a vertical swipe that should cause a scroll. Once that's done, the event is sent to the table cell "as normal", whence vie the responder chain it eventually reaches the tableview a second time. You can tell them apart because the second touchesBegan comes with a touchUp phase.

Still, until I figure this out completely (or someone else does!) I have tried out other ways of building the interface functionality I'm after.

Also I get inexplicable behaviour when I try to capture double-clocks with delayed method calls: it goes into a loop passing the same event again and again. If however I override the touchesBegan etc in TableCell, with no super call (ie to consume them and prevent their second appearance) things are better --- except the delayed call loses its location information, and you can't figure out which cell it was that was double-tapped.

All very mysterious. Sorry I don't know more at this stage!

Carroll

PS: Please excuse typos etc --- I am not at my usual site.