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# contactDelegate

A delegate that is called when two physics bodies come in contact with each other.

```
weak var contactDelegate: (any SCNPhysicsContactDelegate)? { get set }
```

## Discussion

A contact is created when two physics bodies overlap and one of the physics bodies has a [`collisionBitMask`](/documentation/SceneKit/SCNPhysicsBody/collisionBitMask) property that overlaps with the other body’s [`categoryBitMask`](/documentation/SceneKit/SCNPhysicsBody/categoryBitMask) property.

---

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