点击分享按钮时，QLPreviewController崩溃，内部一致性笔尖束错误

Question

我正在以模态方式呈现QLPreviewController。一切正常 - 它弹出，显示预览项目和一切。但是，一旦点击了分享按钮，应用程序就会在设备上和模拟器中崩溃：

2013-05-03 20:10:53.563 appname[16860:c07] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Could not load NIB in bundle: 'NSBundle <{{app_path}}> (loaded)' with name '_UIDocumentActivityViewController''

以下是相关代码：

#pragma mark HVSchedulesDelegate

- (void)schedulePDFReceived {
    QLPreviewController *previewController = [[QLPreviewController alloc] init];
    [previewController setDataSource:self];

    [self presentViewController:previewController animated:YES completion:nil];
}

#pragma mark QLPreviewControllerDataSource

- (NSInteger) numberOfPreviewItemsInPreviewController:(QLPreviewController *)controller {
    return 1;
}

- (id <QLPreviewItem>)previewController:(QLPreviewController *)controller previewItemAtIndex:(NSInteger)index {
    return [NSURL fileURLWithPath:self.schedulesProxy.pdfPath];
}