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# SCNPhysicsContactDelegate

Methods you can implement to respond when a contact or collision occurs between two physics bodies in a scene.

```
protocol SCNPhysicsContactDelegate : NSObjectProtocol
```

## Overview

To receive contact messages, you set the [`contactDelegate`](/documentation/SceneKit/SCNPhysicsWorld/contactDelegate) property of an [`SCNPhysicsWorld`](/documentation/SceneKit/SCNPhysicsWorld) object. SceneKit calls your delegate methods when a contact begins, when information about the contact changes, and when the contact ends.

## Topics

### Responding to Contact Events

[`physicsWorld(_:didBegin:)`](/documentation/SceneKit/SCNPhysicsContactDelegate/physicsWorld(_:didBegin:))

Tells the delegate that two bodies have come into contact.

[`physicsWorld(_:didUpdate:)`](/documentation/SceneKit/SCNPhysicsContactDelegate/physicsWorld(_:didUpdate:))

Tells the delegate that new information is available about an ongoing contact.

[`physicsWorld(_:didEnd:)`](/documentation/SceneKit/SCNPhysicsContactDelegate/physicsWorld(_:didEnd:))

Tells the delegate that a contact has ended.


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