球在不可见的盒子内弹跳/移动 ios/xcode

Question

我希望当用户摇动设备时，球会在屏幕上的对象内部发出嘎嘎声。我假设我需要设置一个不可见的盒子让它碰撞。它是随机移动还是遵循预定义的路径都没有关系，以最简单的为准。

我想我理解代码的“摇晃激活”部分，只是我不确定的球/物体运动

Answer 1

这应该可行：

//You need an @property (nonatomic, strong) UIDynamicAnimator *animator; in your .h
self.animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.viewToBounceAroundIn];

UICollisionBehavior *collision = [[UICollisionBehavior alloc] initWithItems:@[self.viewThatBouncesAround]];
collision.translatesReferenceBoundsIntoBoundary = YES;
[self.animator addBehavior:collision];

UIPushBehavior *push = [[UIPushBehavior alloc] initWithItems:@[self.viewThatBouncesAround] mode:UIPushBehaviorModeInstantaneous];
push.magnitude = 1; //Play with this, it's how much force is applied to your object
push.angle = 0; //play with this too
[self.animator addBehavior:push];

我从编译器中输入了这个 - 如果它有效，请告诉我。这个想法是您使用UIKitDynamics 作为物理引擎，使用UICollisionBehavior 让项目在盒子内反弹，并使用UIPushBehavior 施加初始力。

如果该物品对您来说减速太快，或者从墙壁反弹时失去太多能量，您可以调整其属性：

UIDynamicItemBehavior *behavior = [[UIDynamicItemBehavior alloc] initWithItems:@[self.itemThatBouncesAround]];
behavior.friction = 0; //no friction. play with this.
behavior.elasticity = 1;; //completely elastic, play with this.
[self.animator addBehavior:behavior];