gistfile1.txt

[[FBSession activeSession] closeAndClearTokenInformation];

if (NSClassFromString(@"ACAccountStore")) {
    ACAccountStore *accountStore = [[ACAccountStore alloc] init];
    if ([accountStore respondsToSelector:NSSelectorFromString(@"ACAccountStoreRemoveCompletionHandler")]) {
        ACAccountType *fbType = [accountStore accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierFacebook];
        NSArray *accounts = [accountStore accountsWithAccountType:fbType];
        ACAccount *account = [accounts lastObject];
        if (account) {
            [accountStore renewCredentialsForAccount:account completion:^(ACAccountCredentialRenewResult renewResult, NSError *error) {
                  
            }];
        }
    }
}