Methods your app can implement to respond when physics bodies come into contact.
An object that implements the SKPhysicsContactDelegate protocol can respond when two physics bodies with overlapping contactTestBitMask values are in contact with each other in a physics world. To receive contact messages, you set the contactDelegate property of a SKPhysicsWorld object. The delegate is called when a contact starts or ends.
You can use the contact delegate to play a sound or execute game logic, such as increasing a player’s score, when a contact event occurs. The following code shows how to display a shockwave effect when two nodes with the name ball come into contact. The code only creates the effect when the collision impulse is above a specified threshold: