AppDelegate

//1. 创建窗口
 self.window = UIWindow(frame: UIScreen.mainScreen().bounds) 
//2. 显示窗口
 self.window?.makeKeyAndVisible() 
let viewCtrl = ViewController()
/  self.window?.rootViewController = viewCtrl 
//3. 创建导航控制器，至少需要放入一个页面（第一个页面也叫做根视图控制器） 
let navCtrl = UINavigationController(rootViewController: viewCtrl) 
//文字//图片 
      navCtrl.navigationBar.tintColor = UIColor.redColor() 
//整个导航条的颜色
 navCtrl.navigationBar.barTintColor = UIColor.greenColor() 
self.window?.rootViewController = navCtrl

ViewController

    self.view.backgroundColor = UIColor.redColor()
    /
    self.title = "第一页"
    用于设置导航条
    / self.navigationItem.title = "第一页"
    //设置导航条中间部分
    let v = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 10)) v.backgroundColor = UIColor.blueColor()
    self.navigationItem.titleView = v
    //设置左侧
    // self.navigationItem.leftBarButtonItem = UIBarButtonItem(title: "左侧", style: .Plain, target: self, action: #selector(leftClicked))
    // self.navigationItem.leftBarButtonItem = UIBarButtonItem(barButtonSystemItem: .Bookmarks, target: self, action: #selector(leftClicked)) let originImage = UIImage(named: "1.png")
    //图片总是显示原始颜色
    let image = originImage?.imageWithRenderingMode(.AlwaysOriginal) self.navigationItem.leftBarButtonItem = UIBarButtonItem(image: image, style: .Plain, target: self, action: #selector(leftClicked))
    let btn = UIButton(type: .System)
    btn.frame = CGRect(x: self.view.frame.size.width / 2 - 75, y: self.view.frame.size.height / 2 - 25, width: 150, height: 50) btn.setTitle("下一页", forState: .Normal)
    btn.addTarget(self, action: #selector(didClicked(_:)), forControlEvents: .TouchUpInside) self.view.addSubview(btn)
}
func leftClicked() {
    print("leftClicked")
}
func didClicked(sender: UIButton)
{ let secondCtrl = SecondViewController()
    
    //每一个“已经”处于导航控制器中的页面，它的navigationController属性不为空
    self.navigationController?.pushViewController(secondCtrl, animated: true)
}