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# animation(_:didReachProgressMark:)

Sent to the delegate when an animation reaches a specific progress mark.

```
nonisolated optional func animation(_ animation: NSAnimation, didReachProgressMark progress: NSAnimation.Progress)
```

## Parameters

`animation`

A running `NSAnimation` object that has reached a progress mark.

`progress`

A `float` value (typed as `NSAnimationProgress`) that indicates a progress mark of `animation`.

## Discussion

The delegate typically implements this method to perform some animation effect for the time slice indicated by `progress`, such as redrawing objects in a view with new coordinates or changing the frame location or size of a window or view. As an alternative to this delegation message, you may choose to observe the [`progressMarkNotification`](/documentation/AppKit/NSAnimation/progressMarkNotification) notification.

---

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