UIAttachmentBehavior－动画效果：依附，关联

最新推荐文章于 2025-03-18 10:14:14 发布

翻译最新推荐文章于 2025-03-18 10:14:14 发布 · 5.2k 阅读

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#UIAttachmentBehavior #UIDynamicAnimator #动画 #关联运动

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本文介绍如何使用UIKit Dynamics实现iOS应用中的拖动动画效果。通过创建拖动手势识别器、设置锚点视图及关联动画行为，使得一个视图能够跟随用户的拖动而平滑移动。文中详细展示了创建视图、添加手势识别器及配置动态动画系统的具体步骤。

1。关联动画项，使其中一个运动后，相关联的对象也随之一起运动

2。初始化

- (instancetype)initWithItem:(id<UIDynamicItem>)item attachedToAnchor:(CGPoint)point

- (instancetype)initWithItem:(id<UIDynamicItem>)item offsetFromCenter:(UIOffset)p1 attachedToAnchor:(CGPoint)point

e.g.

- (void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];

[self createGestureRecognizer]; //创建拖动
[self createSmallSquareView];
[self createAnchorView]; //创建锚点，基准视图，
[self createAnimatorAndBehaviors]; //创建关联动画
}

- (void) createSmallSquareView{
self.squareView = [[UIView alloc] initWithFrame: CGRectMake(0.0f, 0.0f, 80.0f, 80.0f)];
self.squareView.backgroundColor = [UIColor greenColor];
self.squareView.center = self.view.center;

self.squareViewAnchorView = [[UIView alloc] initWithFrame: CGRectMake(60.0f, 0.0f, 20.0f, 20.0f)];
self.squareViewAnchorView.backgroundColor = [UIColor brownColor];
[self.squareView addSubview:self.squareViewAnchorView];

[self.view addSubview:self.squareView];
}
- (void) createAnchorView{

self.anchorView = [[UIView alloc] initWithFrame: CGRectMake(120.0f, 120.0f, 20.0f, 20.0f)];
self.anchorView.backgroundColor = [UIColor redColor];
[self.view addSubview:self.anchorView];
}
- (void) createGestureRecognizer{
UIPanGestureRecognizer *panGestureRecognizer =
[[UIPanGestureRecognizer alloc] initWithTarget:self
action:@selector(handlePan:)];
[self.view addGestureRecognizer:panGestureRecognizer];
}

- (void) handlePan:(UIPanGestureRecognizer *)paramPan{ //拖动的点作为锚点
CGPoint tapPoint = [paramPan locationInView:self.view];
[self.attachmentBehavior setAnchorPoint:tapPoint];
self.anchorView.center = tapPoint;
}
- (void) createAnimatorAndBehaviors{

self.animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];

/* Create collision detection */
UICollisionBehavior *collision = [[UICollisionBehavior alloc]
initWithItems:@[self.squareView]];
collision.translatesReferenceBoundsIntoBoundary = YES;
// self.attachmentBehavior = [ [UIAttachmentBehavior alloc] initWithItem:self.squareView
// attachedToAnchor:self.anchorView.center];

// self.attachmentBehavior = [ [UIAttachmentBehavior alloc] initWithItem:self.squareViewAnchorView
// attachedToAnchor:self.anchorView.center];

//squareView视图右上方的点会跟着锚点一起动，带动了squareView整个视图跟着锚点一起动
UIOffset offset = UIOffsetMake(self.squareViewAnchorView.center.x, self.squareViewAnchorView.center.y);
self.attachmentBehavior = [[UIAttachmentBehavior alloc] initWithItem:self.squareView
offsetFromCenter:offset //偏移
attachedToAnchor:self.anchorView.center];

[self.animator addBehavior:collision];
[self.animator addBehavior:self.attachmentBehavior];
}