I added this code to remove the "Edit button" at least for the version 26.0 and higher. We have to find out at which version this is functional again....
(void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
UINavigationBar *morenavbar = navigationController.navigationBar;
UINavigationItem *morenavitem = morenavbar.topItem;
morenavitem.rightBarButtonItem = nil;
}