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 {  FBSDKLoginManager *login = [[FBSDKLoginManager alloc] init];  [login logInWithReadPermissions:@[@"email"] handler:^(FBSDKLoginManagerLoginResult *result, NSError *error) {     if (error) {         // Process error     } else if (result.isCancelled) {         // Handle cancellations     } else {         // If you ask for multiple permissions at once, you         // should check if specific permissions missing         if ([result.grantedPermissions containsObject:@"email"]) {             // Do work         }     } }]; } 

BUT the result is always nil and error code is 304, am I missing something?

Answer 1

I had a similar problem.

After initialising FBSDKLoginManager I added a line to flush out the data and the (Facebook)Token:

FBSDKLoginManager *loginmanager= [[FBSDKLoginManager alloc]init];     [loginmanager logOut]; 

Hope this helps.

---

Thus, exactly as the OP asks, "am I missing something"?

Yes, the following standard example code which is seen everywhere, is simply wrong:

-(IBAction)facebookLoginClick:(id)sender { FBSDKLoginManager *login = [[FBSDKLoginManager alloc] init]; ---- ONE MAGIC LINE OF CODE IS MISSING HERE ---- [login logInWithReadPermissions:@[@"email"]    handler:^(FBSDKLoginManagerLoginResult *result, NSError *error)     {     if (error) {...}     else if (result.isCancelled) {...}     else { // (NB for multiple permissions, check every one)        if ([result.grantedPermissions containsObject:@"email"])           { NSLog(@"%@",result.token); }        } }]; } 

you must do this:

-(IBAction)facebookLoginClick:(id)sender { FBSDKLoginManager *login = [[FBSDKLoginManager alloc] init]; [login logOut];   //ESSENTIAL LINE OF CODE [login logInWithReadPermissions:@[@"email"]    handler:^(FBSDKLoginManagerLoginResult *result, NSError *error)     {     if (error) {...}     else if (result.isCancelled) {...}     else { // (NB for multiple permissions, check every one)        if ([result.grantedPermissions containsObject:@"email"])           { NSLog(@"%@",result.token); }        } }]; } 

Otherwise, very simply, the app will not work if the user happens to change FB accounts on the device. (Unless they happen to for some reason re-install the app!)

Once again - the popular sample code above simply does not work (the app goes in to an endless loop) if a user happens to change FB accounts. The logOut call must be made.