使用facebook登录IOS延迟查找用户的电子邮件

Question

The request and login occurs all fine but with delay that disrupts what I want to do.

When the user taps startButton I call the facebook login method and that occurs fine, session is open and then call 'populateUserDetails' to get the user's email that information comes with a delay that makes my variables name and email goes empty to my service because the signIn method is called before the user's email and name from populateUserDetails arrive.

Login button action and facebook methods:

- (IBAction)actionButtonStart:(id)sender
{
    if (FBSession.activeSession.state == FBSessionStateOpen
        || FBSession.activeSession.state == FBSessionStateOpenTokenExtended) {

        [FBSession.activeSession closeAndClearTokenInformation];

    } else {

        [FBSession openActiveSessionWithReadPermissions:@[@"basic_info"]
                                           allowLoginUI:YES
                                      completionHandler:
         ^(FBSession *session, FBSessionState state, NSError *error) {

             [self sessionStateChanged:session state:state error:error];
         }];
    }
}

- (void)populateUserDetails
{
    if (FBSession.activeSession.isOpen) {
        [[FBRequest requestForMe] startWithCompletionHandler:
         ^(FBRequestConnection *connection,
           NSDictionary<FBGraphUser> *user,
           NSError *error) {
             if (!error) {
                 NSLog(@"%@", user.name);
                 NSLog(@"%@", [user objectForKey:@"email"]);
                 self.nome = user.name;
                 self.email = [user objectForKey:@"email"];
             }
         }];
    }
}

- (void)sessionStateChanged:(FBSession *)session state:(FBSessionState) state error:(NSError *)error
{
    if (!error && state == FBSessionStateOpen){
        NSLog(@"Session opened");

        [self populateUserDetails];
        [self signIn];

        return;
    }
    if (state == FBSessionStateClosed || state == FBSessionStateClosedLoginFailed){
        NSLog(@"Session closed");
    }
    if (error){
        NSLog(@"Error");
        NSString *alertText;
        NSString *alertTitle;

        if ([FBErrorUtility shouldNotifyUserForError:error] == YES){

            alertTitle = @"Something went wrong";
            alertText = [FBErrorUtility userMessageForError:error];
            //[self showMessage:alertText withTitle:alertTitle];
        } else {

            if ([FBErrorUtility errorCategoryForError:error] == FBErrorCategoryUserCancelled) {
                NSLog(@"User cancelled login");

            } else if ([FBErrorUtility errorCategoryForError:error] == FBErrorCategoryAuthenticationReopenSession){
                alertTitle = @"Session Error";
                alertText = @"Your current session is no longer valid. Please log in again.";
                //[self showMessage:alertText withTitle:alertTitle];

              https://developers.facebook.com/docs/ios/errors
            } else {
                //Get more error information from the error
                NSDictionary *errorInformation = [[[error.userInfo objectForKey:@"com.facebook.sdk:ParsedJSONResponseKey"] objectForKey:@"body"] objectForKey:@"error"];

                alertTitle = @"Something went wrong";
                alertText = [NSString stringWithFormat:@"Please retry. \n\n If the problem persists contact us and mention this error code: %@", [errorInformation objectForKey:@"message"]];
                //[self showMessage:alertText withTitle:alertTitle];
            }
        }

        [FBSession.activeSession closeAndClearTokenInformation];
        //[self userLoggedOut];
    }
}

- (void)loginView:(FBLoginView *)loginView handleError:(NSError *)error {
    NSString *alertMessage, *alertTitle;

    if ([FBErrorUtility shouldNotifyUserForError:error]) {
        alertTitle = @"Facebook error";
        alertMessage = [FBErrorUtility userMessageForError:error];

    } else if ([FBErrorUtility errorCategoryForError:error] == FBErrorCategoryAuthenticationReopenSession) {
        alertTitle = @"Session Error";
        alertMessage = @"Your current session is no longer valid. Please log in again.";

    } else if ([FBErrorUtility errorCategoryForError:error] == FBErrorCategoryUserCancelled) {
        NSLog(@"user cancelled login");

    } else {
        alertTitle  = @"Something went wrong";
        alertMessage = @"Please try again later.";
        NSLog(@"Unexpected error:%@", error);
    }

    if (alertMessage) {
        [[[UIAlertView alloc] initWithTitle:alertTitle
                                    message:alertMessage
                                   delegate:nil
                          cancelButtonTitle:@"OK"
                          otherButtonTitles:nil] show];
    }
}

Sign in method

- (void)signIn
{

    if([GenericService checkConnection]){

        GenericService *service = [[GenericService alloc] initWithDelegate:self andCallback:@selector(answerSignIn:)];
        service.metodo = 1;
        service.messageLoading = @"Wait...";
        service.url = @"http://myservice.com/signIn.json";
        [service addParameter:self.name withKey:@"name"];
        [service addParameter:self.email withKey:@"email"];
        [service request];

    }
}

- (NSString *) answerSignIn:(NSDictionary *)answer {

    NSLog(@"%@", [answer description]);

    NSString *sucess = [answer objectForKey:@"sucesso"];

    if (sucess)
        [self.navigationController pushViewController:self.tabBarController animated:YES];

    return sucess;
}

Answer 1

This is happening because the FBRequest block is asynchronous, ie it performs the FBRequest in the background, as to allow your app to continue other processes while it's busy fetching the information. So yes, there will be a delay, but in order to still have the info you need when you need it, call the signIn method within your FBRequest block in populateUserDetails instead of calling it in sessionStateChanged:state:error: , like so:

- (void)populateUserDetails
{
    if (FBSession.activeSession.isOpen) {
        [[FBRequest requestForMe] startWithCompletionHandler:
         ^(FBRequestConnection *connection,
           NSDictionary<FBGraphUser> *user,
           NSError *error) {
             if (!error) {
                 NSLog(@"%@", user.name);
                 NSLog(@"%@", [user objectForKey:@"email"]);
                 self.nome = user.name;
                 self.email = [user objectForKey:@"email"];

                 [self signIn];
             }
         }];
    }
}