Some online services, especially those which run on proprietary devices such as game consoles, have built-in, standardized user interfaces that they bring up whenever certain operations are launched. For example, adding a friend, sending an invitation to join a match, or registering a credit card may bring up a game-independent form, overlay, screen, or workflow that the user must navigate to access that feature. This is generally done to ensure that certain sensitive interactions are always handled the same way, and are controlled by the company that owns the online service, rather than individual third-party developers. These features are also not standard across every online service, and in some cases, may only exist on one particular service or system. To handle these disparate features, the Online Subsystem collects them all and provides the External UI Interface to interact with them.
Using External User Interfaces
External user interfaces will notify the Online Subsystem when they close by calling various delegates specific to the External UI Interface.
In addition, changes that they make may result in calls to delegates from other parts of the Online Subsystem, such as the Login Interface.
Because any given function of the External UI Interface is likely not to be implemented on most online services, it is important to pay attention to the return values of these functions.
A return value of false indicates that the given user function is not supported on the current online service, or otherwise failed to open.
This type of failure will not cause any delegates to be called, as there is no operation to perform.
Showing a Message Box
If you wish to display a message in the platform's built-in style, call ShowPlatformMessageBox.
This is commonly done to show "system" messages (as opposed to "game" messages), such as informing users of patches or other updates, or providing feedback on errors like trying to activate multiplayer-only features while offline.
This operation does not fire a delegate when complete.
Viewing a User Profile
To view the user profile overlay, call ShowProfileUI with the FUniqueNetId of the user requesting to see the profile, and the user who owns the profile.
When overlay closes, your provided delegate (of type FOnProfileUIClosedDelegate) will be called.
Logging In
While the Identity Interface is the usual place to handle authentication functionality, certain platforms may require that you go through their user interface flow, or it may simply be more convenient (and more consistent) than writing your own login user interface flow.
The ShowLoginUI will use the current online service's standard login UI, if it exists.
When the user closes the interface, a provided delegate of type FOnLoginUIClosedDelegate will be called.
Changes to the user's login status will still call delegates through the Identity Interface.
Using the Friends List
The ShowFriendsUI will bring up the Friends list, if the online service includes a built-in feature to do so.
For more direct interaction with the Friends list, refer to the Friends Interface page.
Changes made by the user through the external Friends list UI will still result in calls to the appropriate Friends Interface delegates.
Sending an Invitation
To display the built-in UI that provides a list of friends to invite to a game session, call ShowInviteUI with the name of the session.
For more information, refer to the Sessions and Matchmaking page.
Sending a Message to Another User
On services that provide a "mailbox" feature, ShowSendMessageUI will open the UI to send a message.
A delegate of type FOnShowSendMessageUIClosedDelegate can be provided, and will be called when the message UI closes.
A provided FShowSendMessageParams parameter will initialize the interface.
Viewing Achievements
The ShowAchievementsUI function, called with the local user's index, will bring up the built-in interface to review the specified local user's unlocked achievements and compare them with other users.
To manage a user's Achievements, use the Achievements Interface.
Creating or Upgrading an Account
Some online services, particularly on consoles, feature the ability to create and upgrade accounts without going to their websites.
To open the user interfaces for these features, use ShowAccountCreationUI and ShowAccountUpgradeUI.
ShowAccountCreationUI will call a provided FOnAccountCreationUIClosedDelegate upon completion.
Visiting the Store
ShowStoreUI takes a user to the online service's store.
If supported by the online service, developers can also provide a category to browse or a particular product to view within the store by specifying the category name or product ID in an FShowStoreParams data structure.
When the store UI closes, your provided delegate (of type FOnShowStoreUIClosedDelegate) will be called.
Visiting External Websites
If your game sends users to an external website, you can use ShowWebURL to open the site within the system's default browser, and CloseWebURL to close the site when the game determines that the user no longer needs to view the site.
When the site closes, either by user or as the result of a call to CloseWebURL, the FOnShowWebUrlClosedDelegate that was provided to the ShowWebURL function will be called.
When calling ShowWebURL, you can specify much more than just the URL to open.
See the API page for FShowWebUrlParams for further information.