（三）swift新增一个顶部菜单导航视图（UINavigationController

新建方式参考：http://www.52php.cn/article/p-xhhzmpze-rc.html

**右侧底部筛选为：**UINavigationController

新建后台代码参考：http://www.52php.cn/article/p-xhhzmpze-rc.html

后台代码继承原为：UIViewController ，改为 UINavigationController
import UIKit

class FourViewController: UINavigationController {

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view,typically from a nib.


    print("Four");
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

为这个新建视图，关联Class

启动模拟器，运行

底部All Output窗口输出： Four