iOS 6 popover navigation bar issue

Question

In the image above I got this popover with navigation bar, but the navigation bar overlaps the content and I can't find a way to make the content go below the navigation bar. The content of the popover is fetched from the device gallery.

This is the code for getting the content and showing it:

UIImagePickerController *photosMedia = [[UIImagePickerController alloc] init];
photosMedia.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
photosMedia.delegate = self;

popoverController=[[UIPopoverController alloc] photosMedia];
popoverController.delegate = self;
popoverController.popoverContentSize = CGSizeMake(300, 400); // 768 400
imagePickerController.modalPresentationStyle = UIModalPresentationFullScreen;
[popoverController presentPopoverFromRect:btnPhotos.bounds
                   inView:btnPhotos
                   permittedArrowDirections:UIPopoverArrowDirectionAny
                   animated:YES];