---
title: timeStep
framework: scenekit
role: symbol
role_heading: Instance Property
path: scenekit/scnphysicsworld/timestep
---

# timeStep

The time interval between updates to the physics simulation.

## Declaration

```swift
var timeStep: TimeInterval { get set }
```

## Discussion

Discussion SceneKit processes the physics simulation and updates the state of all physics bodies once per the time interval specified by this property. The default value is 1/60 second (a rate of 60 Hz). A faster simulation rate provides more accuracy in simulation results—such as collisions between fast-moving objects—but at a higher cost in CPU time (which may in turn slow down your app’s rendering frame rate). Typically, you should set this property to match your target rendering frame rate (as defined by the preferredFramesPerSecond property of the SCNView object rendering your scene).

## See Also

### Managing the Physics Simulation

- [gravity](scenekit/scnphysicsworld/gravity.md)
- [speed](scenekit/scnphysicsworld/speed.md)
- [updateCollisionPairs()](scenekit/scnphysicsworld/updatecollisionpairs().md)