登录后，Facebook SDK Objective-C触发事件

Question

I'm new to IOS Application Development and this is the first time I've integrated the Facebook SDK into an application. I'm using my initial view controller to authenticate the user via the Facebook SDK and redirect him to another view controller once he is authenticated. Additionally, once he clicks on log out, I want to be able to redirect the user back to this initial view controller.

I'm using the following code (inside the viewDidLoad function) to add the Facebook login button to my view:

FBSDKLoginButton *loginButton = [[FBSDKLoginButton alloc] init];

// setting the facebook button position
float screenHeight = [[UIScreen mainScreen] bounds].size.height;
float screenWidth = [[UIScreen mainScreen] bounds].size.width;
CGPoint origin = CGPointMake(screenWidth/2, screenHeight - 100);

// Optional: Place the button in the center of your view.
loginButton.center = origin;
[self.view addSubview:loginButton];

The button is working fine, but I noticed that right after I login, the [FBSDKAccessToken currentAccessToken] is nil in all the view controller lifecycle functions. Basically, it seems that this value is initialised by the Facebook SDK after my page is loaded.

Is there any way to execute a function right after this access token gets initialised, so that I can successfully redirect to a different controller? or is there any functionality that might help me achieve this behaviour? Similarly, i'd like to be able to redirect the user back to this initial view controller once he clicks the logout button from a different view.

Answer 1

I found that, by far, the easiest solution to this problem would be setting View Controller as a delegate for the login button and implementing the following functions:

First, you have to use this protocol:

@interface LoginController ()<FBSDKLoginButtonDelegate>

Then, set the view Controller as the button's delegate

loginButton.delegate = self;

Finally, you would have to make sure that the following 2 methods are implemented

- (void)  loginButton:(FBSDKLoginButton *)loginButton
didCompleteWithResult:(FBSDKLoginManagerLoginResult *)result
                error:(NSError *)error{
   //use your custom code here
  //redirect after successful login 
}
- (void) loginButtonDidLogOut:(FBSDKLoginButton *)loginButton{
  //use your custom code here
  //redirect after successful logout 
}

Answer 2

I think you have to use FBGraphApi which will give you call back when user will login successfully.

try code below:

-(void)FBLoginWithViewController:(UIViewController *)viewController withCompletion:(FBDataBlock)block
{
    [login logInWithReadPermissions: @[@"public_profile"]
             fromViewController:viewController
             handler:^(FBSDKLoginManagerLoginResult *permissionResult, NSError *error) {
                 if (error) {

                     block(permissionResult,error,nil);

                 } else if (permissionResult.isCancelled) {

                     block(permissionResult,error,nil);

                 } else {

                     [[[FBSDKGraphRequest alloc] initWithGraphPath:@"me" parameters:@{ @"fields" : @"id,name,picture,email,friends"}]
                      startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection, id response, NSError *error) {

                              block(permissionResult,error,response);
                      }];
                 }
             }];

}

By calling above function you will get call back in ComplitionBlock.

Answer 3

Here is the full and complete code to fetch user's information.

FBSDKLoginManager *login = [[FBSDKLoginManager alloc] init];
[login
 logInWithReadPermissions: @[@"public_profile",  @"user_friends", @"email"]
 fromViewController:self
 handler:^(FBSDKLoginManagerLoginResult *result, NSError *error) {
     if (error) {
         DLog(@"Process error======%@",error.description);
         indicators.hidden=YES;
         [indicators stopAnimating];
     } else if (result.isCancelled) {
         DLog(@"Cancelled");
         indicators.hidden=YES;
         [indicators stopAnimating];
     } else {

         if ([FBSDKAccessToken currentAccessToken]) {



             [[[FBSDKGraphRequest alloc] initWithGraphPath:@"me" parameters:@{@"fields": @"id, name, link, first_name, last_name, picture.type(large), email, birthday, bio ,location ,friends ,hometown , gender ,friendlists"}]
              startWithCompletionHandler:^(
                                           FBSDKGraphRequestConnection *connection, id result, NSError *error) {
                  if (!error)
                  {

                      //  NSLog(@"fetched user:%@", result);

                      // [self fetchingFacebookFriends];

                      [defFacebookData setObject:[result objectForKey:@"email"] forKey:@"fbEmail"];

                      [defFacebookData setObject:[result objectForKey:@"id"] forKey:@"fbID"];


                      //PASS ID
                      getFbid  = [result objectForKey:@"id"];
    NSLog(@"getFbid========>%@",getFbid);

                      //PASS FIRST NAME
                      getFbFirstName=[result objectForKey:@"first_name"];

    NSLog(@"first======>%@",getFbFirstName);

                      //PASS LAST NAME
                      getFBlastName=[result objectForKey:@"last_name"];
    NSLog(@"first======>%@",getFBlastName);

                      //PASS EMAIL
                      getFbemail=[result objectForKey:@"email"];
    NSLog(@"first======>%@",getFbemail);

                      //PASS PHONE
                      getfbGender=[result objectForKey:@"gender"];
    NSLog(@"first======>%@",getfbGender);


                      [defFacebookData setObject:[result objectForKey:@"name"] forKey:@"fbName"];

                      // Image
                      FBSDKGraphRequest *request = [[FBSDKGraphRequest alloc]
                                                    initWithGraphPath:[NSString stringWithFormat:@"me/picture?type=large&redirect=false"]
                                                    parameters:nil
                                                    HTTPMethod:@"GET"];
                      [request startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection,
                                                            id fbImageResult,
                                                            NSError *error) {

NSString *strURL = [NSString stringWithFormat:@"%@",[[fbImageResult objectForKey:@"data"] objectForKey:@"url"]];

    NSLog(@"strURL=====>%@",strURL);

[defFacebookData setObject:strURL forKey:@"fbImage"];

                          [defFacebookData synchronize];


                          NSDictionary *fbdict=[NSDictionary dictionaryWithObjectsAndKeys:getFbid,@"id",getFbFirstName,@"first_name",getFBlastName,@"last_name",getFbemail,@"email",getfbGender,@"gender",strURL,@"fbImage", nil];

                          NSLog(@"done=========>%@",fbdict);

     UIStoryboard*storyboard=[AppDelegate storyBoardType];

    NSUserDefaults *defaults =[NSUserDefaults standardUserDefaults];


    BOOL fblogin =[defaults boolForKey:@"KeyEditProfile"];

        if (fblogin)
            {

                UIStoryboard*Storyboard=[AppDelegate storyBoardType];
                DashboardVC* tabbarController = (DashboardVC*)[Storyboard instantiateViewControllerWithIdentifier:@"DashboardVCId"];



                indicators.hidden=YES;
                [indicators stopAnimating];

                [self.navigationController pushViewController:tabbarController animated:YES];

        }

    else
    {
    EditFBVC *cpvc=(EditFBVC*)[storyboard instantiateViewControllerWithIdentifier:@"EditFBVCId"];
    NSLog(@"get fb id  ===%@",getFbid);


    cpvc.dictFacebookdict =fbdict;

    cpvc.strFBlogin =@"fbAllDataValue";

        indicators.hidden=YES;
        [indicators stopAnimating];

    [self.navigationController pushViewController:cpvc animated:YES];

    }
                      }];
                  }
                  else{

                      DLog(@"error is %@", error.description);
                  }
              }];
         }
     }
 }];