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# setOpacity(_:at:)

Sets the opacity value at a specific time within the time range of the instruction.

```
func setOpacity(_ opacity: Float, at time: CMTime)
```

## Parameters

`opacity`

The opacity to be applied at `time`. The value must be between `0.0` and `1.0`.

`time`

A time value within the time range of the composition instruction.

## Discussion

Sets a fixed opacity to apply from the specified time until the next time at which an opacity is set; this is the same as setting a flat ramp for that time range. Before the first time for which an opacity is set, the opacity is held constant at `1.0`; after the last specified time, the opacity is held constant at the last value.

---

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