使UIButton isHighlighted属性可观察

class ButtonObserver: NSObject {
    @objc dynamic var isHighlighted: Bool = false
    
    override init() {
        super.init()
        
        addObserver(self, forKeyPath: "isHighlighted", options: [.old, .new], context: nil)
    }
    
    deinit {
        removeObserver(self, forKeyPath: "isHighlighted")
    }
    
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if keyPath == "isHighlighted" {
            if let newValue = change?[.newKey] as? Bool {
                // 属性值发生变化时执行的操作
                if newValue {
                    // 按钮进入高亮状态
                    print("Button is highlighted")
                } else {
                    // 按钮退出高亮状态
                    print("Button is not highlighted")
                }
            }
        }
    }
}

// 创建一个UIButton对象
let button = UIButton(type: .system)

// 创建一个观察者对象
let observer = ButtonObserver()

// 将观察者对象注册为按钮的观察者
button.addObserver(observer, forKeyPath: "isHighlighted", options: [.old, .new], context: nil)

// 模拟按钮高亮状态变化
button.isHighlighted = true
button.isHighlighted = false

// 移除观察者对象
button.removeObserver(observer, forKeyPath: "isHighlighted")