按下主页按钮时检测iOS

Question

我有几个iOS应用程序都使用相同的端口来监听网络信标。 在主视图中，我使用viewWillDisappear在打开另一个视图时关闭端口，这很有效。 然后我注意到如果我从主视图控制器按下主页按钮而没有打开另一个视图来关闭端口，那么端口保持打开状态，而我的其他应用程序不再能够监听该端口。 然后我尝试使用viewWillUnload，但是当我按下主页按钮时似乎没有调用。

-(void)viewWillUnload
{
    //[super viewWillUnload];
    NSLog(@"View will unload");
    [udpSocket close];
    udpSocket = nil;
}

视图将卸载从未显示在控制台中，这使我相信该方法永远不会被调用。

有没有办法检测何时按下主页按钮，我可以关闭我的端口？

Answer 1

这些是你的选择

在您的app委托中：

- (void)applicationWillResignActive:(UIApplication *)application
{
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later. 
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

- (void)applicationWillTerminate:(UIApplication *)application
{
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}

Answer 2

处理此问题的最简单方法是注册以在视图控制器中接收UIApplicationWillResignActiveNotification通知。

按下主页按钮，锁定和打电话即可发出此事件

- (void) applicationWillResign{
    NSLog(@"About to lose focus");
}

- (void) myVcInitMethod { 
    [[NSNotificationCenter defaultCenter]
        addObserver:self
        selector:@selector(applicationWillResign)
        name:UIApplicationWillResignActiveNotification 
        object:nil];
}

Answer 3

在Swift用户的情况下

你可以这样写

override func viewDidLoad() {
    super.viewDidLoad()

    // code here...

    NSNotificationCenter.defaultCenter().addObserver(
        self,
        selector: "applicationWillResignActive:",
        name: UIApplicationWillResignActiveNotification,
        object: nil)
}

func applicationWillResignActive(notification: NSNotification) {
    print("I'm out of focus!")
}

此外，当您的应用终止时，请不要忘记关闭它

deinit {

    // code here...

    NSNotificationCenter.defaultCenter().removeObserver(self)
}

Answer 4

除了内存不足外，通常不会调用viewWillUnload 。 您最好实现应用程序委托方法 applicationDidEnterBackground:或applicationWillTerminate:并在那里进行工作或向知道如何处理清理过程的应用程序部分发送通知。

Answer 5

除了内存不足外，通常不会调用viewWillUnload。 请改用：

在您的App代表中：

- (void)applicationWillResignActive:(UIApplication *)application
{
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later. 
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

- (void)applicationWillTerminate:(UIApplication *)application
{
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}

或者，如果要在View Controller中使用代码：

- (void)viewDidDisappear:(BOOL)animated
{
//Put code here
}

- (void)viewWillDisappear:(BOOL)animated
{
//Put code here
}

Answer 6

最好使用UIApplicationWillResignActive和UIApplicationDidBecomeActive因为它们捕获'顶部矩形捕获和释放事件'。 我建议使用这个根类：

class VBase: UIViewController {
    fileprivate var listenersActivated = false
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        onStart()
    }
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        onStop()
        removeListeners()
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
        onStop()
        removeListeners()
    }

    internal func iniListeners() {
        if (!listenersActivated) {
            NotificationCenter.default.addObserver(self, selector: #selector(onStop), name: NSNotification.Name.UIApplicationWillResignActive, object: nil)
            NotificationCenter.default.addObserver(self, selector: #selector(onStart), name: NSNotification.Name.UIApplicationDidBecomeActive, object: nil)
            listenersActivated = true
        } else {

        }
    }
    internal func removeListeners() {
        NotificationCenter.default.removeObserver(self)
        listenersActivated = false
    }
    internal func onStop() {

    }
    internal func onStart() {
        iniListeners()
    }

}

覆盖childs中的onStop()和onStart()以捕获所有视图外观/消失

那是，

class SomeViewController: VBase {

...
    override func onStart() {
        super.onStart()
        someFunctionToInitialize()
    }
    override func onStop() {
        super.onStop()
        stopTimer()
        someFunctionToDesctruction()
    }
}