物理仿真

 

@interfaceViewController ()

//声明仿真器属性  保命啊
@property(nonatomic,strong)UIDynamicAnimator *animator;
@property (weak, nonatomic) IBOutlet UIImageView *imageView;

@end


@implementation ViewController
//物理仿真器懒加载
-(UIDynamicAnimator *)animator{
    if (!_animator) {
        //1.创建物理仿真器  指定仿真范围
        _animator = [[UIDynamicAnimator alloc]initWithReferenceView:self.view];
    }
    return _animator;
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
   
    //在添加行为之前 先移除上次的行为
    [self.animator removeAllBehaviors];
   
   
    //获取捕捉的点
    UITouch *touch = [touches anyObject];
    CGPoint point = [touch locationInView:touch.view];
   
    //2.创建捕捉行为 指定元素
    UISnapBehavior *snap = [[UISnapBehavior alloc]initWithItem:self.imageView snapToPoint:point];
   
    //减震 随机系数
    snap.damping = arc4random_uniform(100)/100.0;
   
    //3.添加到物理仿真器中
    [self.animator addBehavior:snap];

}

 

2.重力  碰撞