FB.Init

Updated: Apr 16, 2026

Sets the state of the Facebook SDK, and initializes all platform-specific data structures and behaviors. This function can only be called once during the lifetime of the object; later calls lead to undefined behavior.

Init() relies on properties that are set in the Unity Editor using the Facebook | Edit settings menu option, as detailed below.

Parameters

There are two signatures for this function. The first takes most of its parameters from the Facebook settings in the editor:

public static void Init(
    InitDelegate onInitComplete = null,
    HideUnityDelegate onHideUnity = null,
    string authResponse = null
)

Name	Type	Description	Default
onInitComplete	InitDelegate	A function that will be called once all data structures in the SDK are initialized; any code that should synchronize with the player's Facebook session should be in onInitComplete().	null
onHideUnity	HideUnityDelegate	A function that will be called when Facebook tries to display HTML content within the boundaries of the Canvas. When called with its sole argument set to false, your game should pause and prepare to lose focus. If it's called with its argument set to true, your game should prepare to regain focus and resume play. Your game should check whether it is in fullscreen mode when it resumes, and offer the player a chance to go to fullscreen mode if appropriate.	null
authResponse	string	effective in Web Player only, rarely used A Facebook auth_response you have cached to preserve a session, represented in JSON. If an auth_response is provided, FB will initialize itself using the data from that session, with no additional checks.	null

Properties set via Facebook | Edit Settings in the Unity Editor

Name	Type	Description	Default
appId	string	The Facebook application ID of the initializing app. Required
cookie	bool	Sets a cookie which your server-side code can use to validate a user's Facebook session	true
logging	bool	If true, outputs a verbose log to the Javascript console to facilitate debugging. Effective on Web only.	true
status	bool	If true, attempts to initialize the Facebook object with valid session data.*	true
xfbml	bool	If true, Facebook will immediately parse any XFBML elements on the Facebook Canvas page hosting the app, like the page plugin. Effective on Web only.	false

The Web platform can make use of certain platform-specific attributes which other platforms will safely ignore; see the documentation for the Javascript SDK's FB.init() for details of their function.

Note: Init often requires an asynchronous read operation, and any code that depends on its being completed should be synchronized in the HideUnityDelegate passed into Init().

Examples

FB.Init();

Check out the SDK Examples for a more complete sample usage of where and when to use FB.Init in your Unity application.