How can I use Facebook instance in a ViewController?

I'm having troubles developing an iOS 5 App with Facebook SDK integration. My App has many ViewsController and for each of them I want to get different data from Facebook using different requests (of course). At the moment I can get data only on the AppDelegate (following the official tutorial) but I need to get data in the view controller. I tried 2 option: 1) Instantiate different Facebook instances on each ViewController -It dosent' work, I don't know why but it seems that

- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation; is never called

2 Instantiate the Facebook instance in the AppDelegate and then use that instance in ViewControllers - It don't works because with this code (found here: How do I persist a Facebook instance in multiple IOS view classes?)

- (void)viewDidLoad
{
    [super viewDidLoad];
    AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    Facebook *facebook = [appDelegate facebook];
}

facebook is nil.

Which is the proper way to work?

Solution

(I will edit my answer if you give me after that more feedback.)

I haven't used a lot the Facebook SDK but I remember having that problem when I tried.

The - (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation implementation should be in your app delegate

If you need to access your Facebook instance in just one viewController (let's say MyFacebooViewController)

You can have something like this

#import <UIKit/UIKit.h>
#import "FBConnect.h"

@interface MyFacebookViewController : UIViewController <FBSessonDelegate, FBRequestDelegate>
@property (nonatomic, strong) Facebook *facebook;
...
@end

And your .m file should contain this

#import "MyFacebookViewController.h"
#import "MyAppDelegate.h"

@implementation MyFacebookViewController

@synthesize facebook = _facebook;

-(Facebook *)facebook
{
    if(!_facebook){
        _facebook = [[Facebook alloc] initWithAppId:MY_APP_ID andDelegate:self];
    }
    return _facebook;
}

-(void)viewDidLoad
{
    [super viewDidLoad];
    ((MyAppDelegate *)([[UIApplication sharedApplication] delegate])).facebookViewController = self;
    ...
}

And of course you need to implement your FBSessionDelegate and FBRequestDelegate methods

In the AppDelegate :

#import <UIKit/UIKit.h>
#import "MyFacebookViewController.h"

@interface MyAppDelegate : UIResponder <UIApplicationDelegate>
...
@property (strong, nonatomic) MyFacebookConnectViewController *facebookViewController;
@end

And it's in the implementation file that you need to put the - (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation

@implementation MyAppDelegate

@synthesize facebookViewController = _facebookViewController;
...

- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation
{
    return [self.facebookViewController.facebook handleOpenURL:url];
}

If you still have problems let me know!