Open Radar

 
<Social/SLServiceTypes.h> declares three constants

SOCIAL_EXTERN NSString *const SLServiceTypeTwitter;
SOCIAL_EXTERN NSString *const SLServiceTypeFacebook;
SOCIAL_EXTERN NSString *const SLServiceTypeSinaWeibo;

with no availability attribute, meaning that if they are linked weakly, they don't behave correctly.

The following code fails

#import <Social/Social.h>

/* Compiled with iOS 6 SDK
 * Social.framework weak linked (Optional)
 * Run on iOS 5.1 (simulator and device)
 * Output is:
 * 0x0
 * About to crash
 * +++ EXC_BAD_ACCESS +++
 */

int main(int argc, char *argv[])
{
	@autoreleasepool
	{
		NSLog(@"%p", &SLServiceTypeFacebook);
		if (&SLServiceTypeFacebook)
		{
			NSLog(@"About to crash");
			NSString *serviceType = SLServiceTypeFacebook; // crashes here with EXC_BAD_ACCESS (code=2, address=0x0)
			NSLog(@"Not reached %@", serviceType);
		}
	}
	return 0;
}

because of this incorrect availability.

The constants should have a __attribute__((weak_import)) qualifier so that they behave correctly.