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# requestedUpdateDidBegin()

Indicates that a requested update has begun so that you’ve an opportunity to extend or reload your timeline.

```
optional func requestedUpdateDidBegin()
```

## Discussion

When the date returned by the [`getNextRequestedUpdateDate(handler:)`](/documentation/ClockKit/CLKComplicationDataSource/getNextRequestedUpdateDate(handler:)) method of your data source passes, ClockKit begins a scheduled update of your complication. At the start of that update, it calls this method or the [`requestedUpdateBudgetExhausted()`](/documentation/ClockKit/CLKComplicationDataSource/requestedUpdateBudgetExhausted()) method to let you know that the requested update has begun. These methods are your opportunity to tell ClockKit whether or not you’ve new data to add to your timeline.

If you’ve new data for your timeline, your implementation of this method should call the [`reloadTimeline(for:)`](/documentation/ClockKit/CLKComplicationServer/reloadTimeline(for:)) or [`extendTimeline(for:)`](/documentation/ClockKit/CLKComplicationServer/extendTimeline(for:)) method of the complication server. ClockKit doesn’t ask your data source for new timeline entries unless you call one of those methods. If you do nothing or don’t implement this method, ClockKit calls only the [`getNextRequestedUpdateDate(handler:)`](/documentation/ClockKit/CLKComplicationDataSource/getNextRequestedUpdateDate(handler:)) of your data source to fetch a new update time.

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