Obj-C - Facebook API - Access An Instance?

ironclaw

Hi Folks,

I'm probably just missing something but I'm trying to implement the FaceBook API into my App.

In my AppDelegate I follow the given tutorial from FaceBook:

.h File

Facebook *facebook;

@property (nonatomic, retain) Facebook *facebook;

.m File

//Did Finish Launching

//Facebook 
	
facebook = [[Facebook alloc] initWithAppId:@"APP_ID_XXXXX"];

 [facebook authorize:nil delegate:self];

Now, this works perfectly. I get the Sign In and Authorise working just fine. The problem is, how do I access the "facebook" instance in say "AnotherClass.m" where I might want to do a Status update etc?

//Status Method - In a different class to App Delegate

NSMutableDictionary* params = [NSMutableDictionary dictionaryWithObjectsAndKeys:
								   
@"http://www.deadmau5.com", @"link",
@"Facebook Dialogs From My App",  @"message", nil];
	
[facebook dialog:@"feed" andParams:params andDelegate:self];

This again works, but I have to alloc a Facebook object. Surely can I not use the one in the Delegate?

I've tried a +(void) updateStatus type function in the AppDelegate but as expected, it doesn't work. I get warnings regarding variables in class methods.

Any help greatly appreciated!

fasty

Easy way:

static Facebook *gFacebook = NIL;

+ (Facebook *)facebookInstance
{
   if (gFacebook == NIL)
      gFacebook = [[Facebook alloc] initWithWhateverYouWantHere];
   }
   
   return gFacebook;
}

But since the above is a global, you may as well declare it

extern Facebook* facebook;

More info here:

http://cocoawithlove.com/2008/11/singletons-appdelegates-and-top-level.html

The right way, imo is to pass dependencies to the objects that use them. In your app delegate, have facebook object as before, but pass said object to the classes/controllers that need it. I usually make custom init functions for this purpose.

I'm not saying don't use globals, but they can lead to problems if you're not careful and definitely are not thread safe. For something like a facebook connection you're probably all right.

ironclaw

Cheers for the reply. With relation to this:

// AppDelegate.h

static Facebook *gFacebook = NIL;

+ (Facebook *)facebookInstance
{
   if (gFacebook == NIL)
      gFacebook = [[Facebook alloc] initWithWhateverYouWantHere];
   }
   
   return gFacebook;
}

How would I call this and use it? For example in "AnotherClass.m"? I've never returned a instance like this.

//include AppDelegate.h

facebook = [AppDelegate facebookInstance] //Get instance?

//Use it

[facebook dialog:@"feed" andParams:params andDelegate:self];

fasty

Something like this should do it. All this code is me typing off the top of my head in a language/API I don't always use so no promised that it'll compile or anything! I can help with errors though!

Apple's UIApplication class has a class method called sharedApplication. It gets the global app instance. You can then access the delegate property like so:

Facebook *instance = [[UIApplication sharedApplication].delegate facebookInstance]

So put the function I originally posted into your app delegate class and see how you get on!