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# startEmulation()

Start the card emulation and present a modal user interface to the person using the app.

```
func startEmulation() async throws
```

## Discussion

Set the [`alertMessage`](/documentation/CoreNFC/CardSession/alertMessage) prior to calling this method.

This method throws an error of type [`CardSession.Error`](/documentation/CoreNFC/CardSession/Error) if card emulation fails. Possible error conditions are:

- [`CardSession.Error.systemNotAvailable`](/documentation/CoreNFC/CardSession/Error/systemNotAvailable)
- [`CardSession.Error.accessNotAccepted`](/documentation/CoreNFC/CardSession/Error/accessNotAccepted)
- [`CardSession.Error.systemEligibilityFailed`](/documentation/CoreNFC/CardSession/Error/systemEligibilityFailed)
- [`CardSession.Error.radioDisabled`](/documentation/CoreNFC/CardSession/Error/radioDisabled)

---

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