控制器NavigationController常用于用来做层次化UI导航。类名为UINavigationController。
NavigationController可以通过属性包含多个ViewController、一个UINavigationBar、一个可选的UIToolbar。
以一个共三层的ViewController的案例,来展示NavigationController的使用:
共三层层次化UI
每一级页面内有一个按钮,可以继续导航到下一级页面
每一个页面的导航条的左侧按钮可以返还到上一级
代码如下:
import UIKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
var nav : Nav?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
self.window = UIWindow(frame: UIScreen.main.bounds)
nav = Nav()
self.window!.rootViewController = nav
self.window?.makeKeyAndVisible()
return true
}
}
class Nav: UINavigationController {
var count = 0
var label : UILabel!
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = .white
self.pushViewController(Level1(), animated: true)
}
}
class Level1: UIViewController {
var count = 0
var label : UILabel!
override func viewDidLoad() {
super.viewDidLoad()
self.title = "Level 1"
self.view.backgroundColor = .white
let button = UIButton(type: .system)
button.frame = CGRect(x: 120, y: 100, width: 100, height: 50)
button.setTitle("Dive Into 2",for: .normal)
button.addTarget(self, action: #selector(Level1.buttonAction(_:)), for: .touchUpInside)
view.addSubview(button)
}
func buttonAction(_ sender:UIButton!){
let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.nav?.pushViewController(Level2(), animated: true)
}
}
class Level2: UIViewController {
var count = 0
var label : UILabel!
override func viewDidLoad() {
super.viewDidLoad()
self.title = "Level 2"
self.view.backgroundColor = .white
let button = UIButton(type: .system)
button.frame = CGRect(x: 120, y: 100, width: 100, height: 50)
button.setTitle("Dive Into 3",for: .normal)
button.addTarget(self, action: #selector(Level2.buttonAction(_:)), for: .touchUpInside)
view.addSubview(button)
}
func buttonAction(_ sender:UIButton!){
let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.nav?.pushViewController(Level3(), animated: true)
}
}
class Level3: UIViewController {
var count = 0
var label : UILabel!
override func viewDidLoad() {
super.viewDidLoad()
self.title = "Level 3"
self.view.backgroundColor = .white
let button = UIButton(type: .system)
button.frame = CGRect(x: 120, y: 100, width: 100, height: 50)
button.setTitle("End",for: .normal)
button.addTarget(self, action: #selector(Level3.buttonAction(_:)), for: .touchUpInside)
view.addSubview(button)
}
func buttonAction(_ sender:UIButton!){
}
}
解释下:
把Nav作为UINavigationController的子类,实例化此类并设置到window.rootViewController上
每一层都是继承于UIViewController,类名分别为Level1、Level2、Level3
Nav类视图加载完成后,把第一层Level1压入导航视图
无需任何用户代码,UINavigationController本身默认提供页面的顶部条状区域,它被称为导航条(UINavigationBar)
点击此导航条的左侧按钮可以返还到上一级页面;导航条中间显示当前ViewController的title属性值
**粗体** _斜体_ [链接](http://example.com) `代码` - 列表 > 引用
。你还可以使用@
来通知其他用户。