iOS8 iPad UIActivityViewControllerでクラッシュ

2014-11-05 11:13:00.374 Hoge[276:13937] *** Terminating app due to uncaught exception 'NSGenericException', 
reason: 'UIPopoverPresentationController (<_uialertcontrolleractionsheetregularpresentationcontroller: 0x12ee22f30>)
should have a non-nil sourceView or barButtonItem set before the presentation occurs.'

    activityController.popoverPresentationController.sourceView = self.view; // 追加
    activityController.completionHandler = completionHandler;
    
    // modalで表示
    [self presentViewController:activityController animated:YES completion:^{
        NSLog(@"Activity complete!!");
    }];