直接上代码
import UIKit
class ViewController: UIViewController {
let per = Person()
override func viewDidLoad() {
super.viewDidLoad()
/// 添加观察者
per.addObserver(self, forKeyPath: "name", options: [.new,.old], context: nil)
}
// 点击屏幕通过kvc给Person里面的name赋值
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
let num = Int(arc4random()%10000) + 1
per.setValue("\(num)", forKey: "name")
}
/// KVO监听属性
///
/// - Parameters:
/// - keyPath: 被监听的属性名
/// - object:
/// - change:
/// - context:
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
print(keyPath ?? "")
print("完成回调 -- \(String(describing: per.value(forKey: keyPath!)))")
}
}
import UIKit
class Person: NSObject {
var name:String?
}
