按下主頁按鈕時檢測iOS

Question

我有幾個iOS應用程序都使用相同的端口來偵聽網絡信標。在主視圖中，我使用viewWillDisappear在另一個視圖打開時關閉端口，這非常有效。然後我注意到，如果我從主視圖控制器按下主頁按鈕而沒有打開另一個視圖關閉端口，那麼端口保持打開狀態，而我的其他應用程序不能再監聽該端口。然後我嘗試使用viewWillUnload，但是當我按下主頁按鈕時似乎沒有被調用。

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

查看將卸載永遠不會顯示在控制檯，這導致我相信該方法永遠不會被調用。

有沒有辦法檢測何時按下主頁按鈕，所以我可以關閉我的端口？

Answer 1

這是你的選擇

在你的應用程序代理：

- (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

viewWillUnload通常不叫除了在內存不足的情況。你最好實施application delegate methodsapplicationDidEnterBackground:或applicationWillTerminate:，並在那裏完成工作，或向您的應用程序的知道如何處理清理過程的部分發送通知。

Answer 3

viewWillUnload通常不會調用，除非內存不足。用這些來代替：

在應用程序委託：

- (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，如果你想在你的瀏覽器使用代碼：

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

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

Answer 4

處理最簡單的方法就是註冊在視圖控制器中收到UIApplicationWillResignActiveNotification通知。

該事件在家裏按下按鈕，鎖在一個電話

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

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

Answer 5

在雨燕用戶的情況下發出

，你可以把它寫這樣

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!") 
} 

也，當你的應用程序終止時，別忘了關閉它

deinit { 

    // code here... 

    NSNotificationCenter.defaultCenter().removeObserver(self) 
} 

Answer 6

更好的使用UIApplicationWillResignActive和UIApplicationDidBecomeActive，因爲它們捕獲了「頂部矩形捕獲和釋放事件」。 我會建議使用這根類：

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() 
    } 

} 

覆蓋onStop()和onStart()裏面孩子的捕獲所有視圖出現/消失

也就是說，

class SomeViewController: VBase { 

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