---
title: duration
framework: quartzcore
role: symbol
role_heading: Instance Property
path: quartzcore/cadisplaylink/duration
---

# duration

The time interval between screen refresh updates.

## Declaration

```swift
var duration: CFTimeInterval { get }
```

## Discussion

Discussion This value is in an undefined state until the system calls the target’s selector at least once. You calculate the expected amount of time your app has to render each frame by using targetTimestamp-timestamp. Use targetTimestamp-CACurrentMediaTime() to calculate the actual amount of time.

## See Also

### Configuring a Display Link

- [preferredFrameRateRange](quartzcore/cadisplaylink/preferredframeraterange.md)
- [preferredFramesPerSecond](quartzcore/cadisplaylink/preferredframespersecond.md)
- [isPaused](quartzcore/cadisplaylink/ispaused.md)
- [timestamp](quartzcore/cadisplaylink/timestamp.md)
- [targetTimestamp](quartzcore/cadisplaylink/targettimestamp.md)
- [frameInterval](quartzcore/cadisplaylink/frameinterval.md)