---
title: SKActionTimingFunction
framework: spritekit
role: symbol
role_heading: Type Alias
path: spritekit/skactiontimingfunction
---

# SKActionTimingFunction

The signature for the custom timing block.

## Declaration

```swift
typealias SKActionTimingFunction = (Float) -> Float
```

## Discussion

Discussion The block parameters are defined as follows: The input value will be a value between 0.0 and 1.0, inclusive. The block must also return a value between 0.0 and 1.0. When the input time is 0.0, the output value should be 0.0. When the input time is 1.0, the output value should also be 1.0.

## See Also

### Controlling Action Timing

- [Configuring Action Timing](spritekit/configuring-action-timing.md)
- [duration](spritekit/skaction/duration.md)
- [timingMode](spritekit/skaction/timingmode.md)
- [SKActionTimingMode](spritekit/skactiontimingmode.md)
- [timingFunction](spritekit/skaction/timingfunction.md)
- [speed](spritekit/skaction/speed.md)