如何删除后退按钮文本。当前的后退按钮:所需的后退按钮:这些都不起作用:self.navigationItem.backBarButtonItem?.title="Back"self.backItem?.title=""self.navigationController?.navigationBar.backItem?.title=""self.navigationItem.backBarButtonItem?.title=""self.navigationController?.navigationItem.backBarButtonItem?.title="Back"self.nav
