---
title: trimStart
framework: realitykit
role: symbol
role_heading: Instance Property
path: realitykit/animationdefinition/trimstart
---

# trimStart

The time, in seconds, at which the animation plays.

## Declaration

```swift
var trimStart: TimeInterval? { get set }
```

## Discussion

Discussion This property is nil by default, which plays the animation with time = 0. If you set a value, the animation edits the duration according to the specified beginning time. If you set a negative value for this property, the duration increases and the additional animation data fills in based on the fillMode you choose.

## See Also

### Timing the animation

- [speed](realitykit/animationdefinition/speed.md)
- [delay](realitykit/animationdefinition/delay.md)
- [duration](realitykit/animationdefinition/duration.md)
- [offset](realitykit/animationdefinition/offset.md)
- [trimDuration](realitykit/animationdefinition/trimduration.md)
- [trimEnd](realitykit/animationdefinition/trimend.md)
- [trimmed(start:end:duration:)](realitykit/animationdefinition/trimmed(start:end:duration:).md)