Open an FBSession with Existing Token Data on iOS

Question

I have a backend service that will log me in my app and return an extended facebook token from previous login, possibly from another device (so no credentials cached on this device). I want to use this token to start a Facebook Session. I am using something like:

FBSession* session = [[FBSession alloc] initWithPermissions:@[@"publish_actions"]];
FBAccessTokenData* tokenData = 
[FBAccessTokenData createTokenFromString:token
                             permissions:@[@"publish_actions"]
                          expirationDate:nil
                               loginType:FBSessionLoginTypeTestUser
                             refreshDate:nil];


[session openFromAccessTokenData:tokenData completionHandler:nil];

I am here passing 'nil' for clarity, in my code I am handling the completion and loggin the session object returned which appears to be in an Open state with no errors. When I try and use the session I get an error like:

Error Domain=com.facebook.sdk Code=5 "The operation couldn’t be completed. (com.facebook.sdk error 5.)" UserInfo=0xb8b1680 {com.facebook.sdk:HTTPStatusCode=403, com.facebook.sdk:ParsedJSONResponseKey={
    body =     {
        error =         {
            code = 200;
            message = "(#200) The user hasn't authorized the application to perform this action";
            type = OAuthException;
        };
    };
    code = 403;
}, com.facebook.sdk:ErrorSessionKey=<FBSession: 0xa2b62a0, state: FBSessionStateOpen, loginHandler: 0xa29e9b0, appID: 131721883664256, urlSchemeSuffix: , tokenCachingStrategy:<FBSessionTokenCachingStrategy: 0xa273f60>, expirationDate: 4001-01-01 00:00:00 +0000, refreshDate: 2013-07-26 16:21:10 +0000, attemptedRefreshDate: 0001-12-30 00:00:00 +0000, permissions:(
    email,
    "publish_actions"
)>}

Any suggestions...?

Answer 1

I found a solution: (provided you have an existing token)

First subclass the FBSessionTokenCachingStrategy class as MySessionTokenCachingStrategy and override the method below:

- (FBAccessTokenData *)fetchFBAccessTokenData 
{
    NSMutableDictionary *tokenInformationDictionary = [NSMutableDictionary new];

    // Expiration date
    tokenInformationDictionary[@"com.facebook.sdk:TokenInformationExpirationDateKey"] = [NSDate dateWithTimeIntervalSinceNow: 3600];

    // Refresh date
    tokenInformationDictionary[@"com.facebook.sdk:TokenInformationRefreshDateKey"] = [NSDate date];

    // Token key
    tokenInformationDictionary[@"com.facebook.sdk:TokenInformationTokenKey"] = self.token;

    // Permissions
    tokenInformationDictionary[@"com.facebook.sdk:TokenInformationPermissionsKey"] = self.permissions;

    // Login key
    tokenInformationDictionary[@"com.facebook.sdk:TokenInformationLoginTypeLoginKey"] = @0;

    return [FBAccessTokenData createTokenFromDictionary: tokenInformationDictionary];
}

Then use the class above to create

MySessionTokenCachingStrategy* tokenCachingStrategy = 
[[MySessionTokenCachingStrategy alloc] initWithToken:token
                                      andPermissions:@[@"read_stream"]];



FBSession *session = [[FBSession alloc] initWithAppID: nil
                                          permissions: @[@"read_stream"]]
                                      urlSchemeSuffix: nil
                                   tokenCacheStrategy: tokenCachingStrategy];

    if (session.state == FBSessionStateCreatedTokenLoaded)
    {
        // Set the active session
        [FBSession setActiveSession: session];

        // Open the session, but do not use iOS6 system acount login
        // if the caching strategy does not store info locally on the
        // device, otherwise you could use:
        // FBSessionLoginBehaviorUseSystemAccountIfPresent
        [session openWithBehavior: FBSessionLoginBehaviorWithFallbackToWebView
                completionHandler: ^(FBSession *session,
                                     FBSessionState state,
                                     NSError *error) {
                    if (!error)
                    {
                        if (session.isOpen)
                        {
                            successBlock();
                        }
                    }
                    else
                    {
                        failureBlock([error description]);
                    }
                }];
    }