facebook ios sdk - trouble posting photo using UIImage

anodeyes · 07-09-2011, 08:03 PM

Hi all-

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:

Code:

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:

Code:

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:

Code:

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:

Code:

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.

Thanks so much.

Peace.

Joel

mariano_donati · 07-10-2011, 07:15 PM

That error comes because the "picture" param is actually expecting an NSString object containing an url to the image. You can't upload a picture along a comment. You need to store it on some server before, get its url and pass it as param.
You can only upload a photo if you add it to an album i.e. using photos.upload request.
I haven't tested, but maybe you could upload the photo to an album and see if you can get its url. Since you will not be using the feed dialog for uploading the photo, you'll need to ask for publish_stream permission.

anodeyes · 07-11-2011, 07:23 AM

Thanks so much for taking time to explain that to me. That makes sense.

But I'm left with a lingering question - does this mean that there's really no direct way to post a photo taken with the iPhone camera to Facebook using the Facebook dialog method, and instead I have to use the Facebook Graph method?

mariano_donati · 07-11-2011, 07:28 AM

Well, I really didn't play around with it for a very long time, so I really can't assure that it is not possible. Have you tried uploading it through photos.upload and then trying to get its url and post that along the comment?