override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
//获得一个应用实例,应用实例的核心作用是提供程序运行期间的控制和协作,每个程序必须有且仅有一个应用实例
let app = UIApplication.shared
NotificationCenter.default.addObserver(self, selector: #selector(ViewController.doSomething(_:)), name: .UIApplicationWillResignActive, object: app)
}
@objc func doSomething(_ sender:AnyObject) {//响应退出事件,退出前保存用户数据
print("Saving data before exit.")
}
Xcode9学习笔记72 - 退出系统前的事件处理
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转载自blog.csdn.net/u011728344/article/details/78620671
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