How can we get FQDN (Fully Qualified Domain Name) in IOS and What Api to Use?

I have a use-case were I want to use the the FQDN (Fully Qualified Domain Name) in IOS-Device, which can be used to connect to a Device instead of using the IP-Address. FQDN will be consisting of the machine-name or host-name (Most common term) and the domain-name of the network i.e network-name (local domain assigned to that device). Which IOS Api can be used Here?