我有一个视图控制器，其中有一个默认的 UIview 放置整个屏幕。我在这个视图中添加了几个 UIImageViews（比如 20 个左右）。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）我需要使用 UIPanGestureRecognizer 或触摸事件吗？在这些 UIImageView 之间实现图像拖放的最简单和最简单的方法是什么？请建议？
谢谢！
几个想法。
您可以通过点击手势来实现这一点（例如点击第一个图像视图，点击目标图像视图），但这不是很直观。使用 a 进行适当的拖放UIPanGestureRecognizer对于您的最终用户来说将更加直观。
从技术上讲，您不是从图像视图中拖动图像，而是实际上是在拖动图像视图本身。（如果没有图像视图，图像本身就没有视觉表示。）当您放手时，您将动画化图像视图帧的变化以完成错觉。
如果你有一个 NSArray imageViews，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];
}
Rob 的回答非常好。handlePan我稍微修改了他的方法以允许图像的热交换。
- (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;
}];
}
}
事实上，根本不要使用轻击手势。
秘诀就是使用imageView的superview。
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收到一个 touchesBegan 事件...如果您使用 ImageViewA 并使用以下方法测试它的 rect：
[rect containsPoint:touchPoint];
如果这是真的并且你已经成功地触摸了第一个 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...然后主机视图应收到以下命令：
[newDraggableImageView setFrame:ImageViewA.frame];
[newDraggableImageView setImage:ImageViewA.image];
[hostView addSubview:newDraggableImageView];
现在您可以使用 UIResponder 方法 touchesBegain touchesMoved 和 touchesEnded 在宿主视图上跟踪触摸事件
当你通过 touchesMoved: 将移动的坐标发送到 newDraggableImageView 的框架中......
因为它正在拖动...... touchesEnded 方法之一：
如果图像的框架在第二个拖动点的框架内，那么您可以设置最终的图像视图
if ([frame containsRect:anotherFrame])
ImageViewB.image = draggableImageView.image;
抱歉，这是伪代码...希望您了解逻辑流程...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...测试位置的 imageView 并适当地设置新的图像视图......
祝你好运！和快乐的编码！