import { NotificationCenter } from 'Foundation';
import { UIApplication } from "UIKit"

class MemoryWarningTool {
	static listener: UTSCallback | null;
	
	// 监听截屏
	static listenMemoryWarning(callback: UTSCallback | null) {
		this.listener = callback
		
		// 注册监听截屏事件及回调方法
		// target-action 回调方法需要通过 Selector("方法名") 构建
		const method = Selector("receiveMemoryWarning")
		NotificationCenter.default.addObserver(this, selector = method, name = UIApplication.didReceiveMemoryWarningNotification, object = null)
	}
	
	// 内存警告回调的方法
	// target-action 的方法前需要添加 @objc 前缀
	@objc static receiveMemoryWarning() {
		// 回调
		this.listener?.({})
	}
	
	// 移除监听事件
	static removeListen(callback: UTSCallback | null) {
		this.listener = null
		NotificationCenter.default.removeObserver(this)
		callback?.({})
	}
}

// 开启监听内存警告
export function onMemoryWarning(callback: UTSCallback | null) {
	MemoryWarningTool.listenMemoryWarning(callback)
}

// 关闭监听内存警告
export function offMemoryWarning(callback: UTSCallback | null) {
	MemoryWarningTool.removeListen(callback)
}