我使用 UIDynamicsAnimator 效果很好，除了动画完成后，被推送和反弹的图像是模糊的。请帮我。
@property (nonatomic,weak) IBOutlet UIImageView *someImage;
self.animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];
self.gravity = [[UIGravityBehavior alloc] initWithItems:@[self.someImage]];
CGVector gravityDirection = {-1.0, 0.5};
[self.gravity setGravityDirection:gravityDirection];
self.collision = [[UICollisionBehavior alloc] initWithItems:@[self.someImage]];
self.collision.translatesReferenceBoundsIntoBoundary = YES;
self.itemBehaviour = [[UIDynamicItemBehavior alloc] initWithItems:@[self.someImage]];
self.itemBehaviour.elasticity = 0.5;
[self.animator removeAllBehaviors]; // to avoid problems from the last behaviour animation
[self.collision addBoundaryWithIdentifier:@"barrier"
fromPoint:CGPointMake(444,0)
toPoint:CGPointMake(444,768)];
self.pushBehavior = [[UIPushBehavior alloc] initWithItems:@[self.someImage] mode:UIPushBehaviorModeInstantaneous];
self.pushBehavior.magnitude = 1.0f;
self.pushBehavior.angle = 0.0f;
[self.animator addBehavior:self.pushBehavior];
self.pushBehavior.pushDirection = CGVectorMake(1.0f, 0.0f)
self.pushBehavior.active = YES;
[self.animator addBehavior:self.itemBehaviour];
[self.animator addBehavior:self.collision];
[self.animator addBehavior:self.gravity];