我有一个UITableView,其中的单元格是UITableViewCell的子类,这些子类具有顶部UIView和底部UIView,如果用户拖动手指,则顶部UIView可以左右移动。

我通过向每个UITableViewCell添加一个平移手势识别器来使其工作。很简单的东西。但是我只想要水平平移,但是当它打算向上滚动时,它将检测到整个单元格的垂直平移,这将导致UITableView不移动。

我试图做到这一点,以便仅在用户将手指水平平移超过5px时才能检测到手势,但似乎不起作用。滚动条工作正常,我可以轻按单元格,但是在单元格上滑动了十次,可能只有一次。

我不知道为什么。

相关代码:

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)recognizer {
    if ([recognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
        NSLog(@"hi");
        CGPoint translation = [(UIPanGestureRecognizer *)recognizer translationInView:self];

        if (translation.x > 5 || translation.x < -5) {
            return YES;
        }
        else {
            return NO;
        }
    }
    else {
        return YES;
    }
}

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

我到底应该怎么做才能使此实现更好地工作?

最佳答案

做到这一点的一种不错的方法,而不必弄乱只有在移动了某个值后才开始平移,这是确定手势识别器向哪个方向平移最多并使用该方向。它减少了您所需的代码量,并且在我的测试中效果很好。

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
    if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
        CGPoint translation = [(UIPanGestureRecognizer*)gestureRecognizer translationInView:self.superview];
        return fabsf(translation.x) > fabsf(translation.y)
    }

    return YES;
}

现在,您的视图滑动变得更加简单。此代码允许您向任一方向拖动。
- (void)drag:(UIPanGestureRecognizer *)sender {
    CGPoint translation = [sender translationInView:self.superview];
    CGRect frame = self.upperView.frame;

    switch (sender.state) {
        case UIGestureRecognizerStateChanged:
            frame.origin.x = translation.x;
            [self.upperView setFrame:frame];
            break;
        case UIGestureRecognizerStateBegan:
        case UIGestureRecognizerStateEnded:
        case UIGestureRecognizerStateFailed:
        default:
            break;
    }
}

此外,您可能希望允许手势识别器与其他手势一起工作(例如,处理表视图滚动的识别器),但是gestureRecognizerShouldBegin:中的代码似乎可以毫无问题地处理此动作。
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
    return YES;
}

还要注意,我使用的是self.superview,而不仅仅是self。这是因为文档的translationInView:部分中的这一行:

应该在其坐标系中计算平移手势的平移的视图。如果要调整视图的位置以将其保持在用户的手指下,要求在该视图的 super 视图的坐标系中进行平移。

10-07 19:54
查看更多