---
title: SCNPhysicsCollisionCategory
framework: scenekit
role: symbol
role_heading: Structure
path: scenekit/scnphysicscollisioncategory
---

# SCNPhysicsCollisionCategory

Default values for a physics body’s categoryBitMask and collisionBitMask properties.

## Declaration

```swift
struct SCNPhysicsCollisionCategory
```

## Overview

Overview You specify contact and collision behaviors by defining your own categories for the kinds of bodies your app simulates and setting the categoryBitMask and collisionBitMask properties for each body to determine which kinds of bodies it collides with. Additionally, you can use the contactDelegate property of the physics world to be notified of collisions between bodies. For more details and example usage, see Defining a Body’s Category and Collisions in the class overview.

## Topics

### Constants

- [default](scenekit/scnphysicscollisioncategory/default.md)
- [static](scenekit/scnphysicscollisioncategory/static.md)
- [all](scenekit/scnphysicscollisioncategory/all.md)

### Initializers

- [init(rawValue:)](scenekit/scnphysicscollisioncategory/init(rawvalue:).md)

## Relationships

### Conforms To

- [BitwiseCopyable](swift/bitwisecopyable.md)
- [Equatable](swift/equatable.md)
- [ExpressibleByArrayLiteral](swift/expressiblebyarrayliteral.md)
- [OptionSet](swift/optionset.md)
- [RawRepresentable](swift/rawrepresentable.md)
- [Sendable](swift/sendable.md)
- [SendableMetatype](swift/sendablemetatype.md)
- [SetAlgebra](swift/setalgebra.md)

## See Also

### Working with Contacts and Collisions

- [categoryBitMask](scenekit/scnphysicsbody/categorybitmask.md)
- [contactTestBitMask](scenekit/scnphysicsbody/contacttestbitmask.md)
- [collisionBitMask](scenekit/scnphysicsbody/collisionbitmask.md)
- [continuousCollisionDetectionThreshold](scenekit/scnphysicsbody/continuouscollisiondetectionthreshold.md)