swift语言的学习笔记八(保留了许多ＯＣ的实现)

尽管swift作为一门新语言，但还保留了许多ＯＣ的机制，使得swift和OC更好的融合在一起。如果没有ＯＣ基础的先ＧＯＯＧＬＥ一下。

如：ＫＶＯ，ＤＥＬＥＧＡＴＥ，ＮＯＴＩＦＩＣＡＴＩＯＮ。

详见ＤＥＭＯ。

 import Foundation

 @objc   // 需要打开objc标识，否则@optional编译出错

 protocol kvoDemoDelegate {
 func willDoSomething()
 @optional  func didDoSomething()  //可选实现,
 }

 let ntfname = "test_notification"

 class kvoDemo : NSObject //不写NSObject默认就是从NSObject来的
 {
     var delegate: kvoDemoDelegate!

     var presult : Double = 0.0

     var result : Double {
         get{
             return presult;
         }

         set{
           self.presult = newValue
         }
     }

     init()
     {

     }

     func doSomething()
     {
         if let yet = self.delegate?
         {
             delegate!.willDoSomething()
         }

         for _ in 1..5
         {
             println("i'm doing now,don't touch me,please.")
         }

         if let yet = self.delegate?
         {
             delegate!.didDoSomething!()
         }
     }

     func notificationPost()
     {
         let ntf = NSNotificationCenter.defaultCenter()
         ntf.postNotificationName(ntfname, object :nil, userInfo:nil)
     }

     deinit
     {

     }
 }

测试：

 class ViewController: UIViewController,kvoDemoDelegate {

     //KVO
     override func observeValueForKeyPath(keyPath: String?, ofObject: AnyObject?, change: NSDictionary?, context: CMutableVoidPointer)
     {
         if keyPath == "result"
         {
             var newvalue : AnyObject? = change?.objectForKey("new");
             println("the new value is \(newvalue)")
         }
     }

     //delegate
     func willDoSomething()
     {
         println("i will do it.")
     }

     func didDoSomething()
     {
         println("i had do it.")
     }

     //notification
     func onRecviceNotification(notification:NSNotification)
     {
         println("Recevice notification \(notification)")
     }

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

         var kvo = kvoDemo()
         kvo.addObserver(self, forKeyPath: "result", options: NSKeyValueObservingOptions.New | NSKeyValueObservingOptions.Old, context: nil)

         kvo.result = 280.0

         kvo.removeObserver(self,forKeyPath:"result",context: nil)

         kvo.delegate = self
         kvo.doSomething()

         let ntf = NSNotificationCenter.defaultCenter()
         ntf.addObserver(self, selector:"onRecviceNotification:", name :ntfname, object : nil)
         kvo.notificationPost()
         ntf.removeObserver(self)
     }
 }

结果：

 the new value is 280
 i will do it.
 i'm doing now,don't touch me,please.
 i'm doing now,don't touch me,please.
 i'm doing now,don't touch me,please.
 i'm doing now,don't touch me,please.
 i had do it.
 Recevice notification NSConcreteNotification 0x10be60930 {name = test_notification}