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# render(atTime:arguments:)

Renders a frame of a composition at the specified time.

```
func render(atTime time: TimeInterval, arguments: [AnyHashable : Any]!) -> Bool
```

## Parameters

`time`

The time, in seconds, at which  to render a composition frame. The time must be a positive value or zero.

`arguments`

An optional dictionary that can have any of the entries defined in [Rendering Arguments](/documentation/Quartz/rendering-arguments).

## Return Value

<doc://com.apple.documentation/documentation/Swift/true> if successful.

## Discussion

You need to call this method each time you want to render a frame of the composition.

All OpenGL states are preserved  *except* the following:

- States defined by `GL_CURRENT_BIT`
- Textures on each unit and the environment mode
- Matrix mode

If you are using double buffers, keep in mind that the `renderAtTime:arguments:` method does not swap the front and back buffers of the OpenGL context. You must perform the swap yourself by calling the OpenGL command `flushBuffer` on the context associated with the renderer.

If you are interleaving OpenGL code with rendering of a composition, make sure that the OpenGL context is current. If you are using the <doc://com.apple.documentation/documentation/AppKit/NSOpenGLContext> class, call the <doc://com.apple.documentation/documentation/AppKit/NSOpenGLContext/makeCurrentContext()> method prior to rendering. If you are using the CGL API, call the function `CGLSetCurrentContext(_:)`.

---

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