1： navigationController 的返回按钮自定义

SecondViewController *secondVC = [SecondViewController new];
    
    
    //更改UINavigationController的返回按钮
    UIBarButtonItem *backButton = [[UIBarButtonItem alloc]init];
    backButton.title = @"返回";
    [self.navigationItem setBackBarButtonItem:backButton];
    
    
    [self.navigationController pushViewController:secondVC animated:YES];

navigationController 的返回按钮自定义