Supported:

DNSServiceRefSockFD
DNSServiceProcessResult
DNSServiceRefDeallocate
DNSServiceEnumerateDomains
DNSServiceRegister
DNSServiceBrowse
DNSServiceResolve
DNSServiceConstructFullName

TXTRecordCreate
TXTRecordDeallocate
TXTRecordSetValue
TXTRecordRemoveValue
TXTRecordGetLength
TXTRecordGetBytesPtr
TXTRecordContainsKey
TXTRecordGetValuePtr
TXTRecordGetCount
TXTRecordGetItemAtIndex

Unsupported:

DNSServiceRegisterRecord
DNSServiceQueryRecord
DNSServiceReconfirmRecord
DNSServiceCreateConnection
DNSServiceAddRecord
DNSServiceUpdateRecord
DNSServiceRemoveRecord
DNSServiceSetDefaultDomainForUser