我有一个示例项目，我正在尝试测试这种行为。我有两个 UIImageViews 并排。我希望能够在左侧或右侧 UIImageView 上长按，创建一个半透明的克隆图像，并将其拖动到另一个 UIImageView 以交换图像。
例如，要交换图像，用户可以执行以下操作：
- 点击并按住左侧的 UIImageView
- 触摸坐标处将出现一个克隆的、较小的“幽灵”图像
- 用户将克隆的图片拖到右边的 UIImageView
- 用户将手指从屏幕上松开以“放下”克隆的图像
- 然后左右 UIImageViews 可以淹没他们的图像。
这里有一些图片来说明：
原始状态：
长按左侧 UIImageView 后，将较小的克隆图像添加为子视图：
我可以检测到长按并制作克隆图像，但除非我松开手指并在屏幕上再次触摸，否则我无法平移该图像。
我希望能够一次完成所有操作，而无需用户将手指从屏幕上移开。
我不知道这是否是正确的方法，但这就是我现在的做法。谢谢你的帮助！
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self addLongPressGestureToPiece:leftImageView];
[self addLongPressGestureToPiece:rightImageView];
}
- (void)addLongPressGestureToPiece:(UIView *)piece
{
NSLog(@"addLongPressGestureToPiece");
UILongPressGestureRecognizer *longPressGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPressPiece:)];
[longPressGesture setDelegate:self];
[piece addGestureRecognizer:longPressGesture];
[longPressGesture release];
}
- (void)addPanGestureRecognizerToPiece:(UIView *)piece
{
NSLog(@"addPanGestureRecognizerToPiece");
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panPiece:)];
[panGesture setMaximumNumberOfTouches:1];
[panGesture setDelegate:self];
[piece addGestureRecognizer:panGesture];
[panGesture release];
}
- (void)longPressPiece:(UILongPressGestureRecognizer *)gestureRecognizer
{
UIImageView *piece = (UIImageView*)[gestureRecognizer view];
CGPoint point = [gestureRecognizer locationInView:self.view];
if(gestureRecognizer.state == UIGestureRecognizerStateBegan)
{
NSLog(@"UIGestureRecognizerStateBegan");
// create the semi-transparent imageview with the selected pic
UIImage *longPressImage = [piece image];
UIImageView *draggableImageView = [[UIImageView alloc] initWithFrame:CGRectMake(point.x - longPressImage.size.width/6/2, point.y - longPressImage.size.height/6/2, longPressImage.size.width/6, longPressImage.size.height/6)];
draggableImageView.image = longPressImage;
draggableImageView.alpha = 0.5;
draggableImageView.userInteractionEnabled = YES;
[self.view addSubview:draggableImageView];
[self addPanGestureRecognizerToPiece:draggableImageView];
photoView.userInteractionEnabled = NO;
}
else if(gestureRecognizer.state == UIGestureRecognizerStateChanged)
{
NSLog(@"Changed");
}
else if(gestureRecognizer.state == UIGestureRecognizerStateEnded)
{
NSLog(@"Ended");
photoView.userInteractionEnabled = YES;
}
}
- (void)adjustAnchorPointForGestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
{
NSLog(@"adjustAnchorPointForGestureRecognizer");
if (gestureRecognizer.state == UIGestureRecognizerStateBegan) {
UIView *piece = gestureRecognizer.view;
CGPoint locationInView = [gestureRecognizer locationInView:piece];
CGPoint locationInSuperview = [gestureRecognizer locationInView:piece.superview];
piece.layer.anchorPoint = CGPointMake(locationInView.x / piece.bounds.size.width, locationInView.y / piece.bounds.size.height);
piece.center = locationInSuperview;
}
}
- (void)panPiece:(UIPanGestureRecognizer *)gestureRecognizer
{
NSLog(@"pan piece");
UIView *piece =[gestureRecognizer view];
[self adjustAnchorPointForGestureRecognizer:gestureRecognizer];
CGPoint translation = [gestureRecognizer translationInView:[piece superview]];
// if velocity.y is positive, user is moving down, if negative, then moving up
CGPoint velocity = [gestureRecognizer velocityInView:[piece superview]];
if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged)
{
[piece setCenter:CGPointMake([piece center].x + translation.x, [piece center].y + translation.y)];
[gestureRecognizer setTranslation:CGPointZero inView:[piece superview]];
}
else if([gestureRecognizer state] == UIGestureRecognizerStateEnded)
{
NSLog(@"piece y %f", piece.frame.origin.y);
}
}