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.