How to get access token from FBSession? - ios

Question

I am using the Facebook SDK in order to get user groups in an application
but I am getting a null access token.
My code in viewDidLoad is as follows.
- (void)viewDidLoad
{
[super viewDidLoad];
self.session = [[FBSession alloc] initWithAppID:appID permissions:#[#"basic_info",#"user_groups",#"email"] defaultAudience:FBSessionDefaultAudienceEveryone urlSchemeSuffix:nil tokenCacheStrategy:nil];
[FBSession openActiveSessionWithReadPermissions:#[#"basic_info",#"user_groups",#"email"] allowLoginUI:YES completionHandler:^(FBSession *session, FBSessionState status, NSError *error) {
NSLog(#"Error in Session Opening %#",error.description);
NSLog(#"access Token %#",session.accessTokenData.accessToken);
[FBRequestConnection startWithGraphPath:#"me/groups" parameters:nil HTTPMethod:#"GET" completionHandler:^(FBRequestConnection *connection, id result, NSError *error) {
if (!error) {
NSLog(#"%#",result);
}else
{
NSLog(#"Error %#",error.description);
}
}];
}];
}
OUTPUT of this code is :-
Error in Session Opening (null)
access Token (null)
Error Error Domain=com.facebook.sdk Code=5 "The operation couldn’t be completed. (com.facebook.sdk error 5.)" UserInfo=0x1090acc80 {com.facebook.sdk:HTTPStatusCode=400, com.facebook.sdk:ParsedJSONResponseKey={
body = {
error = {
code = 2500;
message = "An active access token must be used to query information about the current user.";
type = OAuthException;
};
};
code = 400;
}}
As you can see the access token is null..
What am I doing wrong ?
Is there something extra which should be added in this code ?
Thanks

Answer 1

you want this:
session.accessTokenData.accessToken
where 'session' is your FBSession
which you can get from...
if (FBSession.activeSession.state == FBSessionStateCreatedTokenLoaded)
{
// If there's one, just open the session silently, without showing the user the login UI
[FBSession openActiveSessionWithReadPermissions:#[#"public_profile", #"email"]
allowLoginUI:NO
completionHandler:^(FBSession *session, FBSessionState state, NSError *error)
{
NSLog(#"%#", session.accessTokenData.accessToken);
}];
}

Answer 2

Are you using the correct facebook appID? Why not specify nil, i.e.,
self.session = [[FBSession alloc] initWithAppID:nil permissions:#[#"basic_info",#"user_groups",#"email"] defaultAudience:FBSessionDefaultAudienceEveryone urlSchemeSuffix:nil tokenCacheStrategy:nil];
That'd be one less place to go wrong. As it says in FBSession class reference
If nil is passed in the default App ID will be obtained from a call to
<[FBSession defaultAppID]>. The default is nil.
Also, you don't have to alloc/init the FBSession yourself, but if you want to, you should follow the 3-step process specified in FBSession lifecycle, including checking for FBSessionStateCreated before proceeding with one of the open methods, as quoted from FBSession lifecycle:
Instead of calling one of the static openActiveSession* methods, your app can achieve the same flow following these steps:
Call one of the FBSession instance init functions.
Check if the state value has transitioned to FBSessionStateCreated.
If the state value is FBSessionStateCreated, call one of the
FBSession instance
open functions.