我想拖动一个UIView，让它移动附加到其上的其他视图的位置，好像它们都是通过字符串连接的。起始状态将是一堆UIViews聚集在一起。如果你拉出一个项目，它附加的项目将在它与被拖动的视图之间达到最小距离后开始移动。我认为实现这一目标的最佳方法是使用UIDynamicItemBehavior，考虑到我需要将其重新捕捉到适当位置并对其施加权重。如果不做荒谬的代码，我不太清楚如何实现这一点。我所拥有的代码可以在下面看到。不幸的是，我遇到的问题是被拖动的方形项目回到了square2。如果有人有任何建议，我会很乐意澄清是否需要。
- (void)viewDidLoad
{
[super viewDidLoad];
_containmentView = [[UIView alloc] initWithFrame:CGRectMake(0.0, self.view.frame.size.height/2, self.view.frame.size.width, 200)];
[self.view addSubview:_containmentView];
[_containmentView setBackgroundColor:[UIColor greenColor]];
_square = [[UIView alloc]initWithFrame:CGRectMake(200, 0, 100, 100)];
_square.backgroundColor = [UIColor yellowColor];
[_containmentView addSubview:_square];
_square2 = [[UIView alloc]initWithFrame:CGRectMake(100, 0, 100, 100)];
_square2.backgroundColor = [UIColor redColor];
[_containmentView addSubview:_square2];
_animator = [[UIDynamicAnimator alloc]initWithReferenceView:_containmentView];
_gravity = [[UIGravityBehavior alloc]initWithItems:@[_square, _square2]];
_gravity.gravityDirection = CGVectorMake(-1.0, 0.0);
[_animator addBehavior:_gravity];
_collision = [[UICollisionBehavior alloc]initWithItems:@[_square]];
_collision.collisionDelegate = self;
_collision.translatesReferenceBoundsIntoBoundary = YES; //causes the boundary to use the bounds of the reference view supplied to the UIDynamicAnimator
[_animator addBehavior:_collision];
UIDynamicItemBehavior *itemBehaviour = [[UIDynamicItemBehavior alloc] initWithItems:@[_square]];
itemBehaviour.elasticity = 0.6;
[_animator addBehavior:itemBehaviour];
UIPanGestureRecognizer *gesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
[_square addGestureRecognizer:gesture];
UIAttachmentBehavior *attach = [[UIAttachmentBehavior alloc] initWithItem:_square2 attachedToItem:_square];
[_animator addBehavior:attach];
}
-(void)handlePan:(UIPanGestureRecognizer *)gesture
{
CGPoint touchPoint = [gesture locationInView:self.view];
UIView* draggedView = gesture.view;
if (gesture.state == UIGestureRecognizerStateBegan) {
// 1. was the pan initiated from the upper part of the recipe?
UIView* draggedView = gesture.view;
CGPoint dragStartLocation = [gesture locationInView:draggedView];
_draggingView = YES;
_previousTouchPoint = touchPoint;
// [_animator updateItemUsingCurrentState:draggedView];
} else if (gesture.state == UIGestureRecognizerStateChanged && _draggingView) {
// 2. handle dragging
float xOffset = _previousTouchPoint.x - touchPoint.x;
gesture.view.center = CGPointMake(draggedView.center.x - xOffset,
draggedView.center.y);
_previousTouchPoint = touchPoint;
// [_animator updateItemUsingCurrentState:draggedView];
} else if (gesture.state == UIGestureRecognizerStateEnded && _draggingView) {
// 3. the gesture has ended
// [self tryDockView:draggedView];
// [self addVelocityToView:draggedView fromGesture:gesture];
[_animator updateItemUsingCurrentState:draggedView];
_draggingView = NO;
}
}
答案 0 :(得分：5)
您需要使用附件拖动您的形状，因此动画师可以使用其物理引擎计算每个项目的位置。
这是viewDidLoad更新：
- (void)viewDidLoad
{
[super viewDidLoad];
_containmentView = [[UIView alloc] initWithFrame:CGRectMake(0.0, self.view.frame.size.height/2, self.view.frame.size.width, 200)];
[self.view addSubview:_containmentView];
[_containmentView setBackgroundColor:[UIColor greenColor]];
_square = [[UIView alloc]initWithFrame:CGRectMake(200, 0, 100, 100)];
_square.backgroundColor = [UIColor yellowColor];
[_containmentView addSubview:_square];
_square2 = [[UIView alloc]initWithFrame:CGRectMake(100, 0, 100, 100)];
_square2.backgroundColor = [UIColor redColor];
[_containmentView addSubview:_square2];
_animator = [[UIDynamicAnimator alloc]initWithReferenceView:_containmentView];
_gravity = [[UIGravityBehavior alloc]initWithItems:@[_square, _square2]];
_gravity.gravityDirection = CGVectorMake(-1.0, 0.0);
[_animator addBehavior:_gravity];
_collision = [[UICollisionBehavior alloc]initWithItems:@[_square, _square2]];
_collision.translatesReferenceBoundsIntoBoundary = YES;
[_animator addBehavior:_collision];
UIDynamicItemBehavior *itemBehaviour = [[UIDynamicItemBehavior alloc] initWithItems:@[_square, _square2]];
itemBehaviour.elasticity = 0.6;
[_animator addBehavior:itemBehaviour];
UIPanGestureRecognizer *gesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
[_square addGestureRecognizer:gesture];
UIPanGestureRecognizer *gesture2 = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
[_square2 addGestureRecognizer:gesture2];
UIAttachmentBehavior *attach = [[UIAttachmentBehavior alloc] initWithItem:_square2 attachedToItem:_square];
attach.damping = 1.6;
attach.frequency = 10;
[_animator addBehavior:attach];
}
我添加了重力，pan＆amp;碰撞到两种形状。
这里应该看看你的handlePan方法：
-(void)handlePan:(UIPanGestureRecognizer *)gesture
{
CGPoint touchPoint = [gesture locationInView:_containmentView];
UIView* draggedView = gesture.view;
if (gesture.state == UIGestureRecognizerStateBegan) {
// 1. was the pan initiated from the upper part of the recipe?
_draggingView = YES;
_previousTouchPoint = touchPoint;
// Add a new attachment on the selected view;
self.attachment = [[UIAttachmentBehavior alloc] initWithItem:draggedView attachedToAnchor:touchPoint];
[self.animator addBehavior:self.attachment];
// Could temporarily remove gravity here
} else if (gesture.state == UIGestureRecognizerStateChanged && _draggingView) {
// 2. handle dragging
[self.attachment setAnchorPoint:touchPoint];
} else if (gesture.state == UIGestureRecognizerStateEnded && _draggingView) {
// 3. the gesture has ended
_draggingView = NO;
[self.animator removeBehavior:self.attachment];
// If gravity was removed, add it back here
}
}
您可能希望在拖动时暂时移除重力。只需看看我的评论，看看你能做到哪里（并且不要忘记在拖动结束时把它放回去）。
正如您所看到的，您真的需要更少的编码来处理手势：）。
您可以同时使用附件的阻尼，频率和长度来使形状对拖动手势做出不同的反应。您还可以使用UIDynamicItemBehavior的density属性为形状添加密度。