UIDynamic-吸附-重力-碰撞-物理仿真动画

现实生活中：

运动场物理仿真器
跑步物理仿真行为
人==仿真元素

创建步骤：

1.创建物理仿真器,并且指定仿真范围
2.创建物理仿真行为,并且指定仿真元素
3.将物理仿真行为添加到仿真器中

Demo：
#pragma mark -懒加载,创建物理仿真器,并且指定仿真范围
- (UIDynamicAnimator*)dynamicAni

{

   if(!_dynamicAni) {

     // 1.创建物理仿真器,并且指定仿真范围

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

     }

   return_dynamicAni;

}
#pragma mark -点击屏幕响应事件
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent*)event
{

     //获取当前触摸手指,以及位置

     //UITouch *touch = [touches anyObject];

     //CGPoint point = [touch locationInView:self.view];

     //重力 
     [self gravity];

    //碰撞 
     //[self collision];

     //吸附 
     //[self snapWithPoint:point]; 
}
#pragma mark -重力 
- (void)gravity 
{ 
     // 1.创建物理仿真器,并且指定仿真范围

     // 2.创建物理仿真行为,并且指定仿真元素
     UIGravityBehavior*gravity = [[UIGravityBehavior alloc] initWithItems:@[self.purView]];

     //设置重力的方向 
     //gravity.gravityDirection = CGVectorMake(1, 0); 
     //gravity.gravityDirection = CGVectorMake(0, -1); 
     //gravity.gravityDirection = CGVectorMake(1, 1);
    
     //设置重力的角度 
     //gravity.angle = M_PI_2;

     //设置重力的加速度 
     //gravity.magnitude = 100.0;

     // 3.将物理仿真行为添加到仿真器中 
     [self.dynamicAni addBehavior:gravity];
}
#pragma mark -碰撞,有重力方能碰撞
- (void)collision
{ 
     // 1.创建物理仿真器,并且指定仿真范围
     // 2.创建物理仿真行为,并且指定仿真元素
     // 2.1创建重力仿真行为
     UIGravityBehavior*gravity = [[UIGravityBehavior alloc] initWithItems:@[self.purView]];
     gravity.magnitude=3;

    // 2.2创建碰撞仿真行为
     UICollisionBehavior*collision = [[UICollisionBehavior alloc] initWithItems:@[self.purView,self.redView]];

     //碰撞模式
     //collision.collisionMode = UICollisionBehaviorModeItems;

     //是否设置碰撞的边界,默认边界为物理仿真器边界
     //collision.translatesReferenceBoundsIntoBoundary = YES;

     //添加直线边界
    //[collision addBoundaryWithIdentifier:@"line" fromPoint:CGPointMake(0, 400)  toPoint:CGPointMake(320, 500)];

     //添加图形的边界,贝赛尔曲线边界
     UIBezierPath*path = [UIBezierPath bezierPathWithOvalInRect:self.view.frame];

    [collision addBoundaryWithIdentifier:@"rect" forPath:path];

     // 3.将物理仿真行为添加到仿真器中
     [self.dynamicAni addBehavior:gravity];
     [self.dynamicAni addBehavior:collision];
}
#pragma mark -吸附
- (void)snapWithPoint:(CGPoint)point
{
     // 1.创建物理仿真器,并且指定仿真范围
     // 2.创建物理仿真行为,并且指定仿真元素
     UISnapBehavior*snap = [[UISnapBehavior alloc] initWithItem:self.purViewsnapToPoint:point];

     //设置吸附行为的"减震", 0.0~1.0
     snap.damping=.5;

     //注意:使用吸附行为,默认只有一次,如若想要多次必须移除之前的行为再重新添加
     [self.dynamicAni removeAllBehaviors];

     // 3.将物理仿真行为添加到仿真器中
     [self.dynamicAni addBehavior:snap];
}
#pragma mark - QZone
- (void)QZoneAnimation
{
     UIButton *addButton = [UIButton buttonWithType:UIButtonTypeContactAdd];

     addButton.center=CGPointMake(kScreenW/2,kScreenH-50);

     [addButton addTarget:self action:@selector(addButtonAction) forControlEvents:UIControlEventTouchUpInside];

     [self.view addSubview:addButton];

     //初始化弹出的控件
     UIView*view1 = [[UIView alloc] initWithFrame:CGRectMake(0,0,20,20)];
     view1.backgroundColor= [UIColor greenColor];
     view1.center=CGPointMake(kScreenW/2,kScreenH-50);
     view1.tag=101;

     UIView*view2 = [[UIView alloc] initWithFrame:CGRectMake(0,0,20,20)];
     view2.backgroundColor= [UIColor purpleColor];
     view2.center=CGPointMake(kScreenW/2,kScreenH-50);
     view2.tag=102;

     UIView*view3 = [[UIView alloc] initWithFrame:CGRectMake(0,0,20,20)];
     view3.backgroundColor= [UIColor cyanColor];
     view3.center=CGPointMake(kScreenW/2,kScreenH-50);
     view3.tag=103;

     [self.view insertSubview:view1 belowSubview:addButton];
     [self.view insertSubview:view2 belowSubview:addButton]; 
     [self.view insertSubview:view3 belowSubview:addButton];
}
#pragma mark - addButtonAction
- (void)addButtonAction
{
     //吸附
     //计算坐标
     CGPoint point1 =CGPointMake(kScreenW/2-50,kScreenH-60-50);
     CGPoint point2 =CGPointMake(kScreenW/2,kScreenH-60-100);
     CGPoint point3 =CGPointMake(kScreenW/2+50,kScreenH-60-50);
     CGPoint point =CGPointMake(kScreenW/2,kScreenH-50);

     UIView *view1 = (UIView*)[self.view viewWithTag:101];
     UIView *view2 = (UIView*)[self.view viewWithTag:102];
     UIView *view3 = (UIView*)[self.view viewWithTag:103];

     // 2.物理仿真行为
     UISnapBehavior*snap1 = [[UISnapBehavior alloc] initWithItem:view1  snapToPoint:point1];
     UISnapBehavior*snap2 = [[UISnapBehavior alloc] initWithItem:view2  snapToPoint:point2];
     UISnapBehavior*snap3 = [[UISnapBehavior alloc] initWithItem:view3  snapToPoint:point3];

     UISnapBehavior*snap4 = [[UISnapBehavior alloc] initWithItem:view1  snapToPoint:point];
     UISnapBehavior*snap5 = [[UISnapBehavior alloc] initWithItem:view2  snapToPoint:point];
     UISnapBehavior*snap6 = [[UISnapBehavior alloc] initWithItem:view3  snapToPoint:point];

     if(_isSnap) {

       [self.dynamicAniremoveAllBehaviors];

       // 3.将物理仿真行为添加到仿真器中
       [self.dynamicAni addBehavior:snap1];
       [self.dynamicAni addBehavior:snap2];
       [self.dynamicAni addBehavior:snap3];

     }else{

       [self.dynamicAni removeAllBehaviors];

       snap4.damping=.8;
       snap5.damping=.8;
       snap6.damping=.8;

       // 3.将物理仿真行为添加到仿真器中
       [self.dynamicAni addBehavior:snap4];
       [self.dynamicAni addBehavior:snap5];
       [self.dynamicAni addBehavior:snap6];
     }
     _isSnap= !_isSnap;
}

重力：

碰撞：

吸附：

分散：