---
title: updateCollisionPairs()
framework: scenekit
role: symbol
role_heading: Instance Method
path: scenekit/scnphysicsworld/updatecollisionpairs()
---

# updateCollisionPairs()

Forces the physics engine to reevaluate possible collisions between physics bodies.

## Declaration

```swift
func updateCollisionPairs()
```

## Discussion

Discussion By default, SceneKit checks for collisions between physics bodies only once per simulation step. If you directly change the positions of any physics bodies outside of a SCNPhysicsContactDelegate method, call the updateCollisionPairs() method before using any of the methods listed in Searching for Physics Bodies Detecting Contacts Between Physics Bodies.

## See Also

### Related Documentation

- [contactDelegate](scenekit/scnphysicsworld/contactdelegate.md)

### Managing the Physics Simulation

- [gravity](scenekit/scnphysicsworld/gravity.md)
- [speed](scenekit/scnphysicsworld/speed.md)
- [timeStep](scenekit/scnphysicsworld/timestep.md)