ios - UIGestureRecognizer and UITableViewCell issue

Question

I am attaching a UISwipeGestureRecognizer to a UITableViewCell in the cellForRowAtIndexPath: method like so:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];

        UISwipeGestureRecognizer *gesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(didSwipe:)];
        gesture.direction = UISwipeGestureRecognizerDirectionRight;
        [cell.contentView addGestureRecognizer:gesture];
        [gesture release];
    }
    return cell;
}

However, the didSwipe method is always getting called twice on successful swipe. I initially thought this was because the gesture starts and ends, but if I log out the gestureRecognizer itself, they are both in the "Ended" state:

-(void)didSwipe:(UIGestureRecognizer *)gestureRecognizer {

    NSLog(@"did swipe called %@", gestureRecognizer);
}

Console:

2011-01-05 12:57:43.478 App[20752:207] did swipe called <UISwipeGestureRecognizer: 0x5982fa0; state = Ended; view = <UITableViewCellContentView 0x5982c30>; target= <(action=didSwipe:, target=<RootViewController 0x5e3e080>)>; direction = right>
2011-01-05 12:57:43.480 App[20752:207] did swipe called <UISwipeGestureRecognizer: 0x5982fa0; state = Ended; view = <UITableViewCellContentView 0x5982c30>; target= <(action=didSwipe:, target=<RootViewController 0x5e3e080>)>; direction = right>

I really really don't know why. I tried obviously checking for the Ended state, but that is no help as they both come in as "Ended" anyway... Any ideas?

Answer 1

Instead of adding the gesture recognizer to the cell directly, you can add it to the tableview in viewDidLoad.

In the didSwipe-Method you can determine the affected IndexPath and cell as follows:

-(void)didSwipe:(UIGestureRecognizer *)gestureRecognizer {

  if (gestureRecognizer.state == UIGestureRecognizerStateEnded) {
        CGPoint swipeLocation = [gestureRecognizer locationInView:self.tableView];
        NSIndexPath *swipedIndexPath = [self.tableView indexPathForRowAtPoint:swipeLocation];
        UITableViewCell* swipedCell = [self.tableView cellForRowAtIndexPath:swipedIndexPath];
        // ...
  }
}