facebook ios sdk - trouble posting photo using UIImage

Question

I'd be grateful for any suggestions as to how to deal with a problem I'm having posting an image to Facebook.

The following code works just as I would expect:

NSMutableDictionary* params = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                 @"http://myserver/img.png", @"picture",
                 @"My Testing", @"name",
                 @"Enter some text...",  @"message",
                 nil];

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

However, I really want to use an image that I capture from my camera. I've set up the code to do that earlier in my application and I've put the image on the screen. So, I tried to do this:

CGRect contextRect  = CGRectMake(0, 0, 320, 436);
UIGraphicsBeginImageContextWithOptions(contextRect.size, YES, 1);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

I've tested this code and newImage is a valid UIImage that I can place and manipulate just as I'd expect. However, when I try to integrate it into the Facebook dialog as follows:

NSMutableDictionary* params = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                 newImage, @"picture",
                 @"My Testing", @"name",
                 @"Enter some text...",  @"message",
                 nil];

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

I get these two ridiculous messages in the console: -[UIImage length]: unrecognized selector sent to instance 0x1c9420 CoreAnimation: ignoring exception: -[UIImage length]: unrecognized selector sent to instance 0x1c9420

So, as a test, I thought I'd try importing an image into my project and accessing it directly. This is the exact image as I referenced online in the first example, so I know it should work. But even when I try this:

UIImage *newImage = [UIImage imageNamed:@"BaB.png"];

I get the same error messages as above.

I see in the Facebook documentation that the "picture" key is supposed to use the URL to an image. But I've seen some examples online that indicate that folks are using an UIImage instead of just an URL.

Clearly, I'm doing something wrong, but I have no idea what it might be.

I'd be very grateful for any pointers as to how to proceed.

Answer 1

A summarized answer that outlines the process...key point is to include the access_token in the graph calls since the facebook-ios-sdk doesn't do this automatically:

1)Update to the latest facebook-ios-sdk.
2)Instantiate with app id.

      self.facebook = [[Facebook alloc] initWithAppId:kApplicationFBID]; 

3) Authorize the app including publish_stream

  NSArray * neededPermissions = [[[NSArray alloc] initWithObjects:@"user_about_me", @"publish_stream", @"user_photos", nil] autorelease];
  [facebook authorize:neededPermissions delegate:appDelegate];

4) Ensure app delegate fBDidLogin captures and stores the access token & expiration in user defaults (for later optimization of login process).

    -(void)fbDidLogin {
        DebugLog(@"New Access Token: %@", [facebook accessToken] );
        NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
        [defaults setObject:[facebook accessToken] forKey:@"FBAccessTokenKey"];
        [defaults setObject:[facebook expirationDate] forKey:@"FBExpirationDateKey"];
        [defaults synchronize];
    }

5) Confirm valid access token (non nil and not expired)...otherwise re authorize app per above.
6) Capture image to UIImage & call this noting the critical addition of the access_token. This will auto create an album for your app and put the image there and post it on the wall per my testing.

-(void)postImageToAlbum:(UIImage *)image {
  NSMutableDictionary *params = [NSMutableDictionary dictionaryWithObjectsAndKeys:
    image, @"source", 
    @"caption desc", @"message",             
    nil];
  [facebook requestWithGraphPath:[NSString stringWithFormat:@"/me/photos?access_token=%@", self.facebook.accessToken]
  andParams:params andHttpMethod:@"POST" andDelegate:self];
}

7) Check for id result in FBRequestDelegate method

    -(void)request:(FBRequest *)request didLoad:(id)result {
        NSLog(@"Request didLoad: %@ ", [request url ]);
        if ([result isKindOfClass:[NSArray class]]) {
            result = [result objectAtIndex:0];
        }
        if ([result isKindOfClass:[NSDictionary class]]){

        }
        if ([result isKindOfClass:[NSData class]]) {
        }
        NSLog(@"request returns %@",result);
     }

8) DO NOT USE a test user account for testing...currently it will auth the test account and provide an access token but when you try to use graph api it will return unexpected errors. You may be alright if you are using web version vs native app setting in dev.facebook.com since supposedly you can create test users and associate them with the app but I haven't tried that.

Good Luck!