Adding Social Media and Other Online Services - Marmalade SDK Mobile Game Development Essentials - page 248

After authorizing (or indeed disallowing) the Facebook App, our application will
regain focus and the login callback function will be triggered to say whether the
process was successful or not. If the Facebook app was not authorized or there is no
Internet connection available, login will fail.
Logging back out of Facebook again is also simple. All we have to do is make a call
to s3eFBSession_Logout , passing the s3eFBSession pointer as its only argument.
In practice we only ever need to log out of Facebook on closing our application or if
you specifically want to log off to allow different user credentials to be used instead.
The session will not expire or become invalid as long as our application is executing.
Posting a message to a user's wall
We'll now take a look at one of the most common things that games use Facebook
for: posting a message to the user's wall to alert their friends to a new high score or
some in-game achievement.
In order to do this we'll be making use of the Facebook Graph API. There are other
ways, but the Graph API is the most up-to-date way of doing so and doesn't look
likely to be replaced any time soon.
For more information on the Facebook Graph API take a look at the web
page http://developers.facebook.com/docs/reference/
api/ , and for details about wall posts take a look at http://
developers.facebook.com/docs/reference/api/post/ .
To begin making a Facebook Graph API request, we use the function s3eFBRequest_
WithGraphPath . This function takes as arguments the session pointer, the desired
Facebook Graph path, and the HTTP method to use (GET or POST). The Graph path
and HTTP method are both specified as null-terminated strings.
The function will return a pointer to an s3eFBRequest structure representing the
new request if it is successful, or NULL if it fails.
With the request structure created, we can now add the various parameters we
need to it using the functions s3eFBRequest_AddParamNumber and s3eFBRequest_
AddParamString . Both functions take the s3eFBRequest structure pointer and a
null-terminated string for the parameter name as their first two parameters. The
third parameter is a 64-bit integer value (Marmalade defines a type called int64 for
this) for the former function call, or a const char pointer to a null terminated string
for the latter function.