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# start(completionHandler:)

Asynchronously starts the haptic engine.

```
func start(completionHandler: (@Sendable ((any Error)?) -> Void)? = nil)
```

## Parameters

`completionHandler`

The closure the system calls to indicate whether the server started successfully or encountered an error.

## Discussion

> Important:
> You can call this method from synchronous code using a completion handler, as shown on this page, or you can call it as an asynchronous method that has the following declaration:
> 
> ```swift
> func start() async throws
> ```
> 
> For information about concurrency and asynchronous code in Swift, see <doc://com.apple.documentation/documentation/Swift/calling-objective-c-apis-asynchronously>.

---

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