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# offset

The zero-based index of the first byte for the read or write request.

```
var offset: Int { get }
```

## Discussion

You can use the value of this property to ensure that the ATT request is attempting to read or write within the proper bounds of the characteristic’s value. For an example of how to take a request’s offset property into account when responding to a read or write request, see [Responding to Read and Write Requests from a Central](https://developer.apple.com/library/archive/documentation/NetworkingInternetWeb/Conceptual/CoreBluetooth_concepts/PerformingCommonPeripheralRoleTasks/PerformingCommonPeripheralRoleTasks.html#//apple_ref/doc/uid/TP40013257-CH4-SW6).

---

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