navigationItem的设置和titleView的设置
设置导航栏中间的标题
self.navigationItem.title = @"title";
设置导航栏的主题颜色
self.navigationBar.barTintColor = [主题色];
设置导航栏的标题文字颜色
[self.navigationController.navigationBar setBarTitleTextAttributes:@{NSForegroundColorAttributeName:[UIColor grayColor]}];
设置背景颜色
[self.navigationBar setBarTintColor:[UIColor redColor]];
设置UIBarButtonItem的样式及图标颜色
    UIBarButtonItem *leftItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemReply target:self action:@selector(leftItemClick)];
        leftItem.tintColor=[UIColor grayColor];
    self.navigationItem.leftBarButtonItem = leftItem;
设置图片成为导航栏的标题
    UIImageView* imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"marker"]];
    self.navigationItem.titleView = imageView;
设置后退按钮的文字,和样式;
    /**
     UIBarButtonItemStylePlain,
     UIBarButtonItemStyleBordered NS_ENUM_DEPRECATED_IOS(2_0, 8_0, "Use UIBarButtonItemStylePlain when minimum deployment target is iOS7 or later"),
     UIBarButtonItemStyleDone,
     */
    UIBarButtonItem *backItem = [[UIBarButtonItem alloc]initWithTitle:@"返回" style:UIBarButtonItemStylePlain target:self action:@selector(backClick)];
    self.navigationItem.backBarButtonItem = backItem;
//点击Cell跳转控制器
    -(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
        UIViewController* VC = [[UIViewController alloc]init];
        [VC.view setFrame:[UIScreen mainScreen].bounds];
        VC.view.backgroundColor = [UIColor redColor];
//设置返回按钮的颜色
self.navigationController.navigationBar.tintColor=[UIColor grayColor];
        [self.navigationController pushViewController:VC animated:YES];
    }
//设置导航栏中title字体颜色及大小
    UILabel *LB = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 100, 30)];
    LB.text = @"ZCL";
    LB.font = [UIFont systemFontOfSize:8];
    LB.textColor = [UIColor redColor];
    //设置位置在中心
    LB.textAlignment = NSTextAlignmentCenter;
    self.navigationItem.titleView = LB;
    //自定义导航栏(搜索框)
    UISearchBar *searchBar = [[UISearchBar alloc] initWithFrame:CGRectMake(0, 0, 50, 30)];
    searchBar.placeholder = @"输入科室进行查找";
    self.navigationItem.titleView = searchBar;