语法：

facebook_login(permissions, ios_login_type)

参数	描述
permissions	The permissions you want to have from the user logging in.
ios_login_type	The iOS only log in type (see the list of constants below).

返回：

N/A（无返回值）

描述

With this function GameMaker Studio 2 will connect to Facebook and ask the user to log into their account. You may also supply additional permission requests in the form of a ds_list that this function then converts into a json array to communicate them to Facebook. There are a wide variety of permissions you may request and they are documented on the Facebook developers pages found here. If you do not wish to ask for any special or extended permissions then you will still need to send a ds_list, but this time it will be empty.

This function is also considered as being asynchronous as while the Facebook login window is open on the screen, the game will continue to run in the background and even once the user has completed the login process, none of the other Facebook functions will work until the facebook_status() returns "AUTHORISED" . Due to the need for an internet connection and the different rates of data transfer, this means that it could be several seconds before this authorisation is received, and all the while the game will still be running.

NOTE: You can now only use the default read permissions to this function. If you require any write permissions or extended read permissions, then you need to call facebook_request_publish_permissions() after logging in. Also note that if your game requests for more than than the public_profile, email and user_friends it will require review by Facebook before it can be used by people other than the game's developers.

There is an extra parameter required for iOS login (other platforms can simply use fb_login_default for the argument). This should be one of the constants listed below:

常量	描述
fb_login_default	Use the default iOS login behaviour (see here for further details).
fb_login_fallback_to_webview	Attempt Facebook login, asking user for credentials if necessary.
fb_login_no_fallback_to_webview	Attempt Facebook login, but no direct request for credentials will be made.
fb_login_forcing_webview	Only attempt WebView login, asking user for credentials
fb_login_use_system_account	Attempt Facebook login, preferring the system account and falling back to a fast app switch if necessary.
fb_login_forcing_safari	Attempt only to login with Safari.

The above listed constants change the login behaviour on iOS, permitting you to select which fallback methods to use (if any) should login fail from through the normal process. For further information pleasesee this Facebook Developer page.

例如：

facebook_init();
var permissions = ds_list_create();
ds_list_add(permissions,"public_profile", "user_friends");
facebook_login(permissions, fb_login_default);
ds_list_destroy(permissions);

The above code will initialize Facebook and then log the current user in, asking for the read permissions given.