創(chuàng)建2個類族阅，動物和食物
import UIKit
class Animal: NSObject {
var name: String!
var age: Int!
var weight: Double!
var food: Food!
}
import UIKit
class Food: NSObject {
var name: String!
}
import UIKit
class ViewController: UIViewController {
let ani = Animal()
override func viewDidLoad() {
super.viewDidLoad()
ani.name = "Zhangsan"
print(ani.name)
//KVC - Key value coding
//keyPath
//無視所有訪問權(quán)限控制
//Swift中，如果變量前面寫了private济锄，就不能用
ani.setValue("Lisi", forKey: "name")
print(ani.name)
print(ani.valueForKey("name"))
let food = Food()
food.name = "骨頭"
ani.food = food
print(ani.food.name)
ani.setValue("耗子", forKeyPath: "food.name")
print(ani.food.name)
print(ani.valueForKeyPath("food.name"))
//KVO - key-value observing
//self觀察ani的name屬性的變化
ani.addObserver(self, forKeyPath: "name", options: [.New], context: nil)
//會通知觀察者
ani.setValue("Dog", forKeyPath: "name")
// ani.name = "Cat"
ani.setValue("Cat", forKey: "name")
ani.removeObserver(self, forKeyPath: "name")
//contentOffset/contentSize/contentInset
}
override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
print(keyPath)
print(object)
print(change)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
運行結(jié)果如下：
Paste_Image.png
Optional( )中可以看到哪些值發(fā)生了變化顾复。
