---
title: collisionBitMask
framework: scenekit
role: symbol
role_heading: Type Property
path: scenekit/scnphysicsworld/testoption/collisionbitmask
---

# collisionBitMask

The key for selecting which categories of physics bodies that SceneKit should test for contacts.

## Declaration

```swift
static let collisionBitMask: SCNPhysicsWorld.TestOption
```

## Discussion

Discussion The value for this key is an NSNumber object containing an NSUInteger value. SceneKit tests for contacts only with physics bodies whose categoryBitMask property overlaps with this bit mask. The default value is all, specifying that searches should test all physics bodies regardless of their category.

## See Also

### Type Properties

- [backfaceCulling](scenekit/scnphysicsworld/testoption/backfaceculling.md)
- [searchMode](scenekit/scnphysicsworld/testoption/searchmode.md)
- [SCNPhysicsWorld.TestSearchMode](scenekit/scnphysicsworld/testsearchmode.md)