Why is my UIPanGestureRecognizer not being detected and firing the method?

Question

I have a UITableView, and I want to attach a UIPanGestureRecognizer to each of the cells, which are subclassed UITableViewCells - ArticleCells. In the awakeFromNib method I add the pan gesture recognizer, but it never fires. Why?

- (void)awakeFromNib {
    [super awakeFromNib];

    self.cellBack = [[CellBack alloc] initWithFrame:CGRectMake(0, 0, self.frame.size.width, 80)];
    [self.contentView addSubview:self.cellBack];

    self.cellFront = [[CellFront alloc] initWithFrame:CGRectMake(0, 0, self.frame.size.width, 80)];
    [self.contentView addSubview:self.cellFront];

    UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pannedCell:)];
    panGestureRecognizer.delegate = self;
}

Which should be firing this method. But I put a breakpoint on it and it never does get fired.

- (void)pannedCell:(UIPanGestureRecognizer *)recognizer {
    if (recognizer.state == UIGestureRecognizerStateBegan) {
        _firstTouchPoint = [recognizer translationInView:self];
        NSLog(@"fired");
    }
    else if (recognizer.state == UIGestureRecognizerStateChanged) {
        NSLog(@"fired");
        CGPoint touchPoint = [recognizer translationInView:self];

        // Holds the value of how far away from the first touch the finger has moved
        CGFloat xPos;

        // If the first touch point is left of the current point, it means the user is moving their finger right and the cell must move right
        if (_firstTouchPoint.x < touchPoint.x) {
            xPos = touchPoint.x - _firstTouchPoint.x;

            if (xPos <= 0) {
                xPos = 0;
            }
        }
        else {
            xPos = -(_firstTouchPoint.x - touchPoint.x);

            if (xPos >= 0) {
                xPos = 0;
            }
        }

        if (xPos > 10 || xPos < -10) {
            // Change our cellFront's origin to the xPos we defined
            CGRect frame = self.cellFront.frame;
            frame.origin = CGPointMake(xPos, 0);
            self.cellFront.frame = frame;
        }
    }
    else if (recognizer.state == UIGestureRecognizerStateEnded) {
        [self springBack];
    }
    else if (recognizer.state == UIGestureRecognizerStateCancelled) {
        [self springBack];
    }
}

And in the .h file I added so it would be notified as implementing it. But it never calls it as I said.

Why?

Answer 1

Did you do this?

[self.contentView addGestureRecognizer:panGestureRecognizer];