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# start(completionHandler:)

Indicates that the framework has started the provider, and provides a completion handler for subclasses to signal their readiness.

```
func start(completionHandler: @escaping ((any Error)?) -> Void)
```

## Parameters

`completionHandler`

A Swift closure or ObjectiveC block for your provider subclass to call after it begins connecting to the server. If you can’t connect, pass a non-nil `error` that describes the error, otherwise pass `nil`.

## Discussion

An [`NEAppPushProvider`](/documentation/NetworkExtension/NEAppPushProvider) subclass must override this method to create a connection with its server.

---

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