You can add any additional modules found in TigaseSwift library or you can create your own based by implementing support for XmppModule protocol.
Here is list of some modules provided by TigaseSwift library:
PresenceModule
Responsible for handling incoming presences and allows to set client presence.
MessageModule
This module is responsible for processing incoming messages, creating/destroying chats and sending messages.
RosterModule
Provides support for retrieval and manipulation of XMPP roster.
MucModule
Provides support for MUC rooms as described in XEP-0045: Multi-User Chat
DiscoveryModule
Provides support for service discovery described in XEP-0030: Service Discovery
StreamManagementModule
Provides support for Stream Management acking and stream resumption as specified in XEP-0198: Stream Management
MessageCarbonsModule
Adds support for forwarding messages delivered to other resources as described in XEP-0280: Message Carbons
VCardModule
Implementation of support for XEP-0054: vcard-temp
PingModule
Allows to check if other XMPP client is available and it is possible to deliver packet to this XMPP client as specified in XEP-0199: XMPP Ping
InBandRegistrationModule
Adds possibility to register XMPP account using XEP-0077: In-Band Registration
MobileModeModule
Provides support for using Tigase Optimizations for mobile devices
CapabilitiesModule
Provides support for XEP-0115: Entity Capabilities which allows for advertisement and automatic discovery of features supported by other clients.