UIKit Dynamics

1.重力效果

    UIImageView * lview =[[UIImageView alloc]initWithFrame:CGRectMake(20, 100, 40, 40)];    lview.image =[UIImage imageNamed:@"zc.jpg"];    [self.view addSubview:lview];    animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];    UIGravityBehavior* gravityBeahvior = [[UIGravityBehavior alloc] initWithItems:@[lview]];    [gravityBeahvior setGravityDirection:CGVectorMake(0.0f, 0.5f)]; //property changed after printing of the book    [animator addBehavior:gravityBeahvior];

注意：UIDynamicAnimator要设置成成员变量才会有用（不知道为什么？）

2.碰撞效果

    UIImageView * lview =[[UIImageView alloc]initWithFrame:CGRectMake(20, 120, 80, 80)];    lview.layer.cornerRadius =40;    lview.layer.masksToBounds =YES;    lview.image =[UIImage imageNamed:@"zc.jpg"];    [self.view addSubview:lview];    UIImageView * wview =[[UIImageView alloc]initWithFrame:CGRectMake(80, 70, 30, 30)];    wview.image =[UIImage imageNamed:@"zc.jpg"];    wview.layer.cornerRadius =15;    wview.layer.masksToBounds =YES;    [self.view addSubview:wview];    animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];    UIGravityBehavior* gravityBeahvior = [[UIGravityBehavior alloc] initWithItems:@[lview,wview]];    [gravityBeahvior setGravityDirection:CGVectorMake(0.0f, 0.5f)];     UICollisionBehavior * collisionBehavior =[[UICollisionBehavior alloc]initWithItems:@[lview,wview]];    [collisionBehavior setCollisionMode: UICollisionBehaviorModeEverything];    collisionBehavior.translatesReferenceBoundsIntoBoundary = YES;    [animator addBehavior:collisionBehavior];    [animator addBehavior:gravityBeahvior];

3.附着效果

    UIImageView * lview =[[UIImageView alloc]initWithFrame:CGRectMake(20, 120, 80, 80)];    lview.layer.cornerRadius =40;    lview.layer.masksToBounds =YES;    lview.image =[UIImage imageNamed:@"zc.jpg"];    [self.view addSubview:lview];    UIImageView * wview =[[UIImageView alloc]initWithFrame:CGRectMake(80, 70, 30, 30)];    wview.image =[UIImage imageNamed:@"zc.jpg"];    wview.layer.cornerRadius =15;    wview.layer.masksToBounds =YES;    [self.view addSubview:wview];    animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];    UIGravityBehavior* gravityBeahvior = [[UIGravityBehavior alloc] initWithItems:@[lview,wview]];    [gravityBeahvior setGravityDirection:CGVectorMake(0.0f, 0.5f)]; //property changed after printing of the book    UICollisionBehavior * collisionBehavior =[[UICollisionBehavior alloc]initWithItems:@[lview,wview]];    [collisionBehavior setCollisionMode: UICollisionBehaviorModeEverything];    collisionBehavior.translatesReferenceBoundsIntoBoundary = YES;    CGPoint frogCenter = CGPointMake(260, 60);    UIAttachmentBehavior *attachmentBehavior = [[UIAttachmentBehavior alloc] initWithItem:lview attachedToAnchor:frogCenter];    [animator addBehavior:collisionBehavior];    [animator addBehavior:gravityBeahvior];    [animator addBehavior:attachmentBehavior];

注：frogCenter是中心点，initWithItem:lview attachedToAnchor:frogCenter：lview以frogCenter为中心点移动。

4.弹跳效果

    UIImageView * lview =[[UIImageView alloc]initWithFrame:CGRectMake(180, 120, 80, 80)];    lview.layer.cornerRadius =40;    lview.layer.masksToBounds =YES;    lview.image =[UIImage imageNamed:@"zc.jpg"];    [self.view addSubview:lview];    UIImageView * wview =[[UIImageView alloc]initWithFrame:CGRectMake(80, 70, 30, 30)];    wview.image =[UIImage imageNamed:@"zc.jpg"];    wview.layer.cornerRadius =15;    wview.layer.masksToBounds =YES;    [self.view addSubview:wview];    animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];    UIGravityBehavior* gravityBeahvior = [[UIGravityBehavior alloc] initWithItems:@[lview,wview]];    [gravityBeahvior setGravityDirection:CGVectorMake(0.0f, 0.5f)]; //property changed after printing of the book    UICollisionBehavior * collisionBehavior =[[UICollisionBehavior alloc]initWithItems:@[lview,wview]];    [collisionBehavior setCollisionMode: UICollisionBehaviorModeEverything];    collisionBehavior.translatesReferenceBoundsIntoBoundary = YES;    CGPoint frogCenter = CGPointMake(lview.center.x, lview.center.y);    UIAttachmentBehavior *attachmentBehavior = [[UIAttachmentBehavior alloc] initWithItem:lview attachedToAnchor:frogCenter];    //设置振幅    [attachmentBehavior setFrequency:1.0f];    //校评动画峰值    [attachmentBehavior setDamping:0.1f];    [attachmentBehavior setLength:100.0f];    [animator addBehavior:collisionBehavior];    [animator addBehavior:gravityBeahvior];    [animator addBehavior:attachmentBehavior];

5.瞬间位移

    lview =[[UIImageView alloc]initWithFrame:CGRectMake(180, 120, 80, 80)];    lview.layer.cornerRadius =40;    lview.layer.masksToBounds =YES;    lview.image =[UIImage imageNamed:@"zc.jpg"];    [self.view addSubview:lview];    UITapGestureRecognizer * gesture =[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(handleSnapGesture:)];    [self.view addGestureRecognizer:gesture];}-(IBAction)handleSnapGesture:(UITapGestureRecognizer*)gesture{    CGPoint point = [gesture locationInView:self.view];    animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];    UISnapBehavior* snapBehavior = [[UISnapBehavior alloc] initWithItem:lview snapToPoint:point];    snapBehavior.damping = 3.05f;    [animator addBehavior:snapBehavior];}

注意：snapBehavior.damping = 3.05f; 数值越大，阻力越大。

6.推力效果

    lview =[[UIImageView alloc]initWithFrame:CGRectMake(180, 120, 80, 80)];    lview.layer.cornerRadius =40;    lview.layer.masksToBounds =YES;    lview.image =[UIImage imageNamed:@"zc.jpg"];    [self.view addSubview:lview];    UITapGestureRecognizer * gesture =[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(handleSnapGesture:)];    [self.view addGestureRecognizer:gesture];    animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];    UICollisionBehavior* collisionBehavior = [[UICollisionBehavior alloc] initWithItems:@[lview]];    collisionBehavior.translatesReferenceBoundsIntoBoundary = YES;    [animator addBehavior:collisionBehavior];    pushBehavior = [[UIPushBehavior alloc] initWithItems:@[lview] mode:UIPushBehaviorModeInstantaneous];    pushBehavior.angle = 0.0;    pushBehavior.magnitude = 0.0;    [animator addBehavior:pushBehavior];}-(IBAction)handleSnapGesture:(UITapGestureRecognizer*)gesture{    CGPoint point = [gesture locationInView:self.view];    CGPoint origin = CGPointMake(CGRectGetMidX(self.view.bounds), CGRectGetMidY(self.view.bounds));    NSLog(@"%f",powf(point.x-origin.x, 2.0));    CGFloat distance = sqrtf(powf(point.x-origin.x, 2.0)+powf(point.y-origin.y, 2.0));    CGFloat angle = atan2(point.y-origin.y,point.x-origin.x);    distance = MIN(distance, 100.0);    //加速度    [pushBehavior setMagnitude:5];    //角度    [pushBehavior setAngle:angle];    [pushBehavior setActive:TRUE];}

注意：powf(point.x-origin.x, 2.0)：point.x-origin.x的平方
sqrtf ：开根号