设置导航栏上面的内容

// 设置左边的返回按钮
viewController.navigationItem.leftBarButtonItem = [UIBarButtonItem itemWithTarget:self action:@selector(back) image:@"navigationbar_back" highImage:@"navigationbar_back_highlighted"];

// 设置右边的更多按钮
viewController.navigationItem.rightBarButtonItem = [UIBarButtonItem itemWithTarget:self action:@selector(more) image:@"navigationbar_more" highImage:@"navigationbar_more_highlighted"];