Question

我有6个uiimageviews，比如img1 - img6。当我触摸并拖动img1时，它会移动。但是当我拖动img1并且当它接近其他uiimageviews时，img1停止移动并且接近它的img开始移动。当我快速拖动图像而不是慢慢拖动图像时会发生这种情况。拖拉也不是那么顺利...... :(

这是我到目前为止所做的......

- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *touch = [[event allTouches] anyObject];
if (CGRectContainsPoint([self.firstImg frame], [touch locationInView:nil]))
{
    [self.view bringSubviewToFront:self.firstImg];
    self.firstImg.center = [touch locationInView:nil];
}
else if (CGRectContainsPoint([self.secondImg frame], [touch locationInView:nil]))
{
    [self.view bringSubviewToFront:self.secondImg];
    self.secondImg.center = [touch locationInView:nil];
}
else if (CGRectContainsPoint([self.thirdImg frame], [touch locationInView:nil]))
{
    [self.view bringSubviewToFront:self.thirdImg];
    self.thirdImg.center = [touch locationInView:nil];
}
else if (CGRectContainsPoint([self.fourthImg frame], [touch locationInView:nil]))
{
    [self.view bringSubviewToFront:self.fourthImg];
    self.fourthImg.center = [touch locationInView:nil];
}
else if (CGRectContainsPoint([self.fifthImg frame], [touch locationInView:nil]))
{          
    [self.view bringSubviewToFront:self.fifthImg];
    self.fifthImg.center = [touch locationInView:nil];
}
else if (CGRectContainsPoint([self.sixthImg frame], [touch locationInView:nil]))
{        
    [self.view bringSubviewToFront:self.sixthImg];
    self.sixthImg.center = [touch locationInView:nil];
}
}

Answer 1

您的实施存在许多问题：

您将nil作为视图传递给locationInView:，这意味着如果移动超视图或支持界面旋转，您将获得不正确的坐标。
您正在将图像视图的中心设置为触摸位置。因此，当用户首次触摸视图时，如果触摸未在视图中精确居中，则视图将跳转到触摸位置的中心。这不是用户期望的行为。
您始终以固定顺序检查视图，而不是从前到后检查视图。这就是为什么“当它接近其他uiimageviews时，img1停止移动并且接近它的img开始移动。”如果触摸超过firstImg，您的代码将始终移动firstImg，即使用户正在拖动secondImg，因为您在检查firstImg之前始终会检查secondImg。
你在重复自己。如果你必须两次写同样的东西，你应该考虑将它分解为一个单独的函数或方法。如果你必须写三次（或更多）相同的东西，你几乎肯定会把它排除在外。

所有这些问题的最简单答案是停止使用touchesMoved:withEvent:及相关方法。相反，为每个图片视图添加UIPanGestureRecognizer：

- (void)makeImageViewDraggable:(UIImageView *)imageView {
    imageView.userInteractionEnabled = YES;
    UIPanGestureRecognizer *panner = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(imageViewPannerDidFire:)];
    [imageView addGestureRecognizer:panner];
}

- (void)imageViewPannerDidFire:(UIPanGestureRecognizer *)panner {
    UIView *view = panner.view;
    [view.superview bringSubviewToFront:view];

    CGPoint translation = [panner locationInView:view];
    CGPoint center = view.center;
    center.x += translation.x;
    center.y += translation.y;
    view.center = center;

    [panner setTranslation:CGPointZero inView:view];
}

- (void)viewDidLoad {
    [super viewDidLoad];
    [self makeImageViewDraggable:self.firstImg];
    [self makeImageViewDraggable:self.secondImg];
    [self makeImageViewDraggable:self.thirdImg];
    [self makeImageViewDraggable:self.fourthImg];
    [self makeImageViewDraggable:self.fifthImg];
    [self makeImageViewDraggable:self.sixthImg];
}

触摸一个UIImageView时禁用其他UIImageViews

1 个答案: