iOS 去掉navigationcontroller返回键文字

//去掉navigationController返回键文字
    self.navigationController.navigationBar.topItem.title = @“";


具体可以这样写：
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
self.navigationController.navigationBar.topItem.title = @"";
}


- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
self.navigationController.navigationBar.topItem.title = @"上一级标题";
}