Question

I get the following error from the alert sheet code below when the user hits the default button:

-[NSRectSet objectForKey:]: unrecognized selector sent to instance
0x400876300

Btw, the code works fine in Snow Leopard but the problem comes up in Lion.

NSMutableDictionary * extrasDict = [[NSMutableDictionary alloc] init];
[extrasDict setObject:@"http://www.google.com" forKey:@"link"];

NSAlert * alert = [NSAlert alertWithMessageText:@"Published Successfully"
                                  defaultButton:@"View Collage on Facebook"
                                alternateButton:nil
                                    otherButton:@"Cancel"
                      informativeTextWithFormat:@"Successfully published to Facebook."];

[alert beginSheetModalForWindow:myWindow
                  modalDelegate:self
                 didEndSelector:@selector(publishedSuccessfullyDidEnd:returnCode:contextInfo:)
                    contextInfo:extrasDict];             


- (void)publishedSuccessfullyDidEnd:(NSAlert *)alert
                         returnCode:(NSInteger)returnCode
                        contextInfo:(void *)contextInfo {
    if (returnCode == NSAlertDefaultReturn) {
        [[NSWorkspace sharedWorkspace] openURL:
         [NSURL URLWithString:[(NSDictionary*)contextInfo objectForKey:@"link"]]]; 
    }       
}

Answer 1

If you’re using garbage collection, store extrasDict in an instance variable – anywhere, doesn’t matter – so it isn’t released at the end of the run loop. You need the dictionary to stick around until the didEndSelector can act on it.