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# settlingDuration

The estimated duration required for the spring system to be considered at rest.

```
var settlingDuration: CFTimeInterval { get }
```

## Discussion

The duration is evaluated for the current animation parameters and may not the same as the [`duration`](/documentation/QuartzCore/CAMediaTiming/duration).

The following code creates a spring animation with a [`duration`](/documentation/QuartzCore/CAMediaTiming/duration) of 2 seconds.

```swift
let spring = CASpringAnimation()

spring.keyPath = "position.x"
spring.fromValue = 0
spring.toValue = 640
spring.damping = 5
spring.duration = 2
```

With a damping coefficient of `5`, the settling duration is approximately 2.85 seconds: the animated layer bounces around the target position several times before settling. However, changing the [`damping`](/documentation/QuartzCore/CASpringAnimation/damping) property to `15` reduces the settling duration to just over 1 second: the animated layer quickly comes to a stop as it reaches the target position.

All of the spring animation’s physical attributes: [`damping`](/documentation/QuartzCore/CASpringAnimation/damping), [`initialVelocity`](/documentation/QuartzCore/CASpringAnimation/initialVelocity), [`mass`](/documentation/QuartzCore/CASpringAnimation/mass) and [`stiffness`](/documentation/QuartzCore/CASpringAnimation/stiffness), can affect the settling duration.

---

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