ios facebook sdk 4.0 login error code 304

Question

I\'ve just updated facebook sdk v4.0

and according the tutorial of Using Custom Login UIs

-(IBAction)facebookLoginClick:(id)sender {

FBSDKLoginManag         


        

Answer 1

Actually, the reason is very simple, you can try following step to reappear this error code easily.

The "Facebook login fail" may have two reasons:

1. you get the user info from facebook fail.
2. you get the user info from facebook success,but upload to your own server fail.

The code in FBSDKLoginManager.m is:

- (void)validateReauthentication:(FBSDKAccessToken *)currentToken withResult:(FBSDKLoginManagerLoginResult *)loginResult
{
  FBSDKGraphRequest *requestMe = [[FBSDKGraphRequest alloc] initWithGraphPath:@"me"
                                                                   parameters:nil
                                                                  tokenString:loginResult.token.tokenString
                                                                   HTTPMethod:nil
                                                                        flags:FBSDKGraphRequestFlagDoNotInvalidateTokenOnError | FBSDKGraphRequestFlagDisableErrorRecovery];
  [requestMe startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection, id result, NSError *error) {
NSString *actualID = result[@"id"];
  if ([currentToken.userID isEqualToString:actualID]) {
    [FBSDKAccessToken setCurrentAccessToken:loginResult.token];
    [self invokeHandler:loginResult error:nil];
  } else {
    NSMutableDictionary *userInfo = [NSMutableDictionary dictionary];
    [FBSDKInternalUtility dictionary:userInfo setObject:error forKey:NSUnderlyingErrorKey];
    NSError *resultError = [NSError errorWithDomain:FBSDKLoginErrorDomain
                                             code:FBSDKLoginUserMismatchErrorCode
                                         userInfo:userInfo];
   [self invokeHandler:nil error:resultError];
  }
}];
}

when currentToken.userID is not equal actualID, the FBSDKLoginUserMismatchErrorCode will throw.

Now, this issue will reappear when user A login facebook fail,but you do not have [FacebookSDKManager logOut] after the fail, the app will cache the accessToken for the user A , and then user A change facebook account to user B, when user B login facebook again,it will reappear this issue.