---
title: "init(duration:animationCurve:)"
framework: appkit
role: symbol
role_heading: Initializer
path: "appkit/nsanimation/init(duration:animationcurve:)"
---

# init(duration:animationCurve:)

Returns an NSAnimation object initialized with the specified duration and animation-curve values.

## Declaration

```swift
init(duration: TimeInterval, animationCurve: NSAnimation.Curve)
```

## Parameters

- `duration`: The number of seconds over which the animation occurs. Specifying a negative number raises an exception.
- `animationCurve`: An NSAnimationCurve constant that describes the relative speed of the animation over its course; if it is zero, the default curve (NSAnimationEaseInOut) is used.

## Return Value

Return Value An initialized NSAnimation instance. Returns nil if the object could not be initialized.

## Discussion

Discussion You can always later change the duration of an NSAnimation object by changing the duration property, even while the animation is running. See “Constants” for descriptions of the NSAnimationCurve constants.

## See Also

### Related Documentation

- [Drawing](appkit/drawing.md)
- [NSAnimation](appkit/nsanimation.md)