Question

我有一个视图控制器，其中有一个默认的UIview放置在整个屏幕上。我在这个视图中添加了几个UIImageViews（比如大约20个）。我想支持在这些UIImageViews之间交换图像。我已经使用UITapGestureRecogniser来处理这些UIImageViews上发生的触摸。我可以在这个UITapGestureRecogniser事件本身下处理这些UIImageViews之间的图像拖放吗？（或）我是否需要使用UIPanGestureRecognizer或触摸事件？在这些UIImageViews之间实现图像拖放的最简单，最简单的方法是什么？请指教？

谢谢！

Answer 1

一些想法。

您可以通过点击手势实现此目的（例如，点按第一张图片视图，点按目标图片视图），但这不是很直观。使用UIPanGestureRecognizer进行适当的拖放对您的最终用户来说更为直观。
从技术上讲，您不是从图像视图中拖动图像，而是实际上是拖动图像视图本身。（图像本身在没有图像视图的情况下没有可视化表示。）当你放开时，你将动画更改图像视图帧以完成幻觉。

如果你有imageViews的NSArray，你可以在他们的超级视图中添加一个手势：

@property (nonatomic, strong) NSMutableArray *imageViews;

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self createImageViewArray];

    UIPanGestureRecognizer *gesture = [[UIPanGestureRecognizer alloc] initWithTarget:self
                                                                              action:@selector(handlePan:)];
    [self.view addGestureRecognizer:gesture];
}

- (void)createImageViewArray
{
    self.imageViews = [NSMutableArray array];

    // add your imageviews to the array any way you want

    ...
}

- (void)handlePan:(UIPanGestureRecognizer *)gesture
{
    static UIImageView *draggedImage = nil;
    static CGRect draggedImageOriginalFrame;

    CGPoint location = [gesture locationInView:gesture.view];

    if (gesture.state == UIGestureRecognizerStateBegan)
    {
        // see if we grabbed an imageview

        draggedImage = [self determineImageForLocation:location];

        // if so, save its old location for future reference and bring it to the front

        if (draggedImage)
        {
            draggedImageOriginalFrame = draggedImage.frame;
            [draggedImage.superview bringSubviewToFront:draggedImage];
        }
    }
    else if (gesture.state == UIGestureRecognizerStateChanged && draggedImage != nil)
    {
        // if we're dragging it, then update its location 

        CGPoint translation = [gesture translationInView:gesture.view];
        CGRect frame = draggedImageOriginalFrame;
        frame.origin.x += translation.x;
        frame.origin.y += translation.y;
        draggedImage.frame = frame;
    }
    else if (draggedImage != nil && (gesture.state == UIGestureRecognizerStateEnded ||
                                     gesture.state == UIGestureRecognizerStateCancelled ||
                                     gesture.state == UIGestureRecognizerStateFailed))
    {
        // if we let go, let's see if we dropped it over another image view

        UIImageView *droppedOver = nil;

        if (gesture.state == UIGestureRecognizerStateEnded)
            droppedOver = [self draggedImageView:draggedImage toLocation:location];

        if (droppedOver == nil)
        {
            // fail; animate the restoring of the view back to it's original position

            [UIView animateWithDuration:0.25
                             animations:^{
                                 draggedImage.frame = draggedImageOriginalFrame;
                             }];
        }
        else
        {
            // succeed; make sure to bring the view we're about to animate to the front

            [droppedOver.superview bringSubviewToFront:droppedOver];

            // animate the swapping of the views

            [UIView animateWithDuration:0.25
                             animations:^{
                                 draggedImage.frame = droppedOver.frame;
                                 droppedOver.frame = draggedImageOriginalFrame;
                             }];
        }
    }
}

// see if we dragged an imageview over one of our imageviews, returning a point
// to the image view we dropped it over

- (UIImageView *)draggedImageView:(UIImageView *)draggedView toLocation:(CGPoint)location
{
    for (UIImageView *imageview in self.imageViews)
        if (CGRectContainsPoint(imageview.frame, location) && imageview != draggedView)
            return imageview;

    return nil;
}

// see if we started the gesture over an imageview
// (turns out that this is the same as "did we drag an image over another",
// but as we're not dragging an image yet, just pass nil)

- (UIImageView *)determineImageForLocation:(CGPoint)location
{
    return [self draggedImageView:nil toLocation:location];
}

Answer 2

罗布的答案很棒。我稍微修改了他的handlePan方法以允许热交换图像。

hot swapping

- (void)handlePan:(UIPanGestureRecognizer *)gesture
{
    static UIImageView *draggedImage = nil;
    static CGRect draggedImageLastFrame;

    CGPoint location = [gesture locationInView:gesture.view];

    if (gesture.state == UIGestureRecognizerStateBegan) {

        // see if we grabbed an imageview

        draggedImage = [self determineImageForLocation:location];

        // if so, save its old location for future reference and bring it to the front

        if (draggedImage) {
            draggedImageLastFrame = draggedImage.frame;
            [draggedImage.superview bringSubviewToFront:draggedImage];
            draggedImage.alpha = 0.6f;
        }

    } else if (gesture.state == UIGestureRecognizerStateChanged && draggedImage != nil) {

        // if we're dragging it, then update its horizontal location

        CGPoint translation = [gesture translationInView:gesture.view];
        CGRect frame = draggedImage.frame;
        frame.origin.x += translation.x;
        draggedImage.frame = frame;
        [gesture setTranslation:CGPointZero inView:gesture.view];

        UIImageView *draggedOver = [self draggedImageView:draggedImage toLocation:location];
        if (draggedOver != nil) {

            // animate the draggedOver image to the the draggedImage's last location

            [UIView animateWithDuration:0.25
                             animations:^{
                                 CGRect currentFrame = draggedOver.frame;
                                 draggedOver.frame = draggedImageLastFrame;
                                 draggedImageLastFrame = currentFrame;
                             }];
        }

    } else if (draggedImage != nil && (gesture.state == UIGestureRecognizerStateEnded ||
                                       gesture.state == UIGestureRecognizerStateCancelled ||
                                       gesture.state == UIGestureRecognizerStateFailed)) {

        // finished, animate the draggedImage into place

        [UIView animateWithDuration:0.25
                         animations:^{
                             draggedImage.frame = draggedImageLastFrame;
                             draggedImage.alpha = 1.0f;
                         }];
    }
}

Answer 3

事实上，根本不要使用轻击手势。

秘诀是使用imageView的超级视图。

你需要3个图像视图......

UIImageView *ImageViewA

UIImageView *ImageViewB

UIImageView *DraggableImageView

假设您单击屏幕并且主机视图获取touchesBegan事件...如果您使用ImageViewA并使用以下方法测试它的rect：

[rect containsPoint:touchPoint];

如果这是真的并且您已成功触摸第一个imageView ...在touchesMoved中开始拖动操作，如下所示：

如果您使用ImageViewA.superview，您将获得视图的主机视图...主机视图应该接收以下命令：

[newDraggableImageView setFrame:ImageViewA.frame];
[newDraggableImageView setImage:ImageViewA.image];
[hostView addSubview:newDraggableImageView];

现在您使用UIResponder方法跟踪主机视图上的触摸事件touchesBegain touchesMoved和touchesEnded

当你浏览touchesMoved：将运动的坐标发送到newDraggableImageView的框架中......

因为它正在拖动...一个touchesEnded方法：

如果图像的帧位于第二个拖动点的帧内，则可以设置最终的图像视图

if ([frame containsRect:anotherFrame])
    ImageViewB.image = draggableImageView.image;

对不起，这是伪代码...希望你理解逻辑流程...将图像添加到主机视图...或应用程序的窗口视图并移动它...一旦移动结束..test对于imageView的位置并适当地设置新的图像视图......

古德纳克！和快乐的编码！

iOS：在UIImageViews之间移动图像

3 个答案: