---
title: allowFastOpen
framework: network
role: symbol
role_heading: Instance Property
path: network/nwparameters/allowfastopen
---

# allowFastOpen

A Boolean that enables sending application data with protocol handshakes.

## Declaration

```swift
final var allowFastOpen: Bool { get set }
```

## Discussion

Discussion When fast open is enabled on a connection, the application is expected to send its early data to be included with the handshake as idempotent data. This data can be sent before or after calling start.

## See Also

### Related Documentation

- [NWConnection.SendCompletion.idempotent](network/nwconnection/sendcompletion/idempotent.md)

### Customizing Connection Options

- [multipathServiceType](network/nwparameters/multipathservicetype-swift.property.md)
- [NWParameters.MultipathServiceType](network/nwparameters/multipathservicetype-swift.enum.md)
- [serviceClass](network/nwparameters/serviceclass-swift.property.md)
- [NWParameters.ServiceClass](network/nwparameters/serviceclass-swift.enum.md)
- [expiredDNSBehavior](network/nwparameters/expireddnsbehavior-swift.property.md)
- [NWParameters.ExpiredDNSBehavior](network/nwparameters/expireddnsbehavior-swift.enum.md)
- [requiresDNSSECValidation](network/nwparameters/requiresdnssecvalidation.md)
- [preferNoProxies](network/nwparameters/prefernoproxies.md)
- [includePeerToPeer](network/nwparameters/includepeertopeer.md)
- [allowLocalEndpointReuse](network/nwparameters/allowlocalendpointreuse.md)
- [acceptLocalOnly](network/nwparameters/acceptlocalonly.md)