ios - How to merge a user signed up by facebook with an exising user signed up with the same email -

i using parse in ios app , there 2 ways of signup, either using email/password or facebook login.

the problem happen when user sign using email/password logout , try sign using facebook account have same email.

i using [pffacebookutils logininbackgroundwithreadpermissions:block: signup facebook creates new user object in users table in parse

now have 2 records same user , can not update record has facebook information user email because parse not allow duplicate emails

so should best solution solve problem?

update

i have used @kriz solution login using plain facebook code either create new user or link user facebook data

- (void)loginwithfacebookwithsuccesscallback:(apisuccesscallback)successcallback                           andfailurecallback:(apifailurecallback)failurecallback {     // login pfuser using facebook     nsarray *permissionsarray = @[@"public_profile", @"email"];      fbsdkloginmanager *login = [[fbsdkloginmanager alloc] init];     [login loginwithreadpermissions: permissionsarray handler:^(fbsdkloginmanagerloginresult *result, nserror *error) {          if (error) {              failurecallback(error);          } else {              fbsdkgraphrequest *request = [[fbsdkgraphrequest alloc] initwithgraphpath:@"me?fields=id,first_name,last_name,email,gender" parameters:nil];               [request startwithcompletionhandler:^(fbsdkgraphrequestconnection *connection, id fbresult, nserror *error) {                  if (!error) {                      nsstring *email = result[@"email"];                      user *existinguser = [self getuserbyemail:email];                       if (existinguser == nil) {                          [self signupnewuserwithemail:email];                      } else {                          // need set current user existinguser                      }                      [self linkcurrentwithaccesstoken:result.token                      successcallback(@{result:result_ok});                  } else {                      failurecallback(error);                  }              }];          }     }];  } 

now problem assign [pfuser currentuser] existing user in case exists

you can try linking new facebook user existing user on parse using [pffacebookutils linkuserinbackground:*... methods.

if (![pffacebookutils islinkedwithuser:user]) {     [pffacebookutils linkuserinbackground:user withreadpermissions:nil block:^(bool succeeded, nserror *error) {         if (succeeded) {             nslog(@"woohoo, user linked facebook!");         }     }]; } 

see parse documentation on linking.

1. login via facebook (do not save user yet)
2. query user table user having same email new fb user
3. if found, link, else, save new user.

update:

linking method fb access token:

[pffacebookutils linkuserinbackground:user                       withaccesstoken:accesstoken                                 block:^(bool succeeded, nserror *error) {     if (succeeded) {         nslog(@"woohoo, user linked facebook!");     } }];