NSMetadataQuery.Notifications.ObserveDidUpdate Method

Definition

Namespace:

Foundation

Assembly:

Xamarin.iOS.dll

Overloads

ObserveDidUpdate(EventHandler<NSNotificationEventArgs>)	Strongly typed notification for the DidUpdateNotification constant.
ObserveDidUpdate(NSObject, EventHandler<NSNotificationEventArgs>)	Strongly typed notification for the DidUpdateNotification constant.

ObserveDidUpdate(EventHandler<NSNotificationEventArgs>)

Strongly typed notification for the DidUpdateNotification constant.

public static Foundation.NSObject ObserveDidUpdate (EventHandler<Foundation.NSNotificationEventArgs> handler);

static member ObserveDidUpdate : EventHandler<Foundation.NSNotificationEventArgs> -> Foundation.NSObject

Parameters

handler

EventHandler<NSNotificationEventArgs>

Method to invoke when the notification is posted.

Returns

NSObject

Token object that can be used to stop receiving notifications by either disposing it or passing it to RemoveObservers(IEnumerable<NSObject>)

Remarks

The following example shows how you can use this method in your code

//
// Lambda style
//

// listening
notification = NSMetadataQuery.Notifications.ObserveDidUpdate ((sender, args) => {
    /* Access strongly typed args */
    Console.WriteLine ("Notification: {0}", args.Notification);
});

// To stop listening:
notification.Dispose ();

//
//Method style
//
NSObject notification;
void Callback (object sender, Foundation.NSNotificationEventArgs args)
{
    // Access strongly typed args
    Console.WriteLine ("Notification: {0}", args.Notification);
}

void Setup ()
{
    notification = NSMetadataQuery.Notifications.ObserveDidUpdate (Callback);
}

void Teardown ()
{
    notification.Dispose ();
}

ObserveDidUpdate(NSObject, EventHandler<NSNotificationEventArgs>)

Strongly typed notification for the DidUpdateNotification constant.

public static Foundation.NSObject ObserveDidUpdate (Foundation.NSObject objectToObserve, EventHandler<Foundation.NSNotificationEventArgs> handler);

static member ObserveDidUpdate : Foundation.NSObject * EventHandler<Foundation.NSNotificationEventArgs> -> Foundation.NSObject

Parameters

objectToObserve

NSObject

The object to observe.

handler

EventHandler<NSNotificationEventArgs>

Method to invoke when the notification is posted.

Returns

NSObject

Token object that can be used to stop receiving notifications by either disposing it or passing it to RemoveObservers(IEnumerable<NSObject>)

Remarks

This method can be used to subscribe for DidUpdateNotification notifications.

// Listen to all notifications posted for any object
var token = NSMetadataQuery.Notifications.ObserveDidUpdate ((notification) => {
	Console.WriteLine ("Observed DidUpdateNotification!");
};

// Listen to all notifications posted for a single object
var token = NSMetadataQuery.Notifications.ObserveDidUpdate (objectToObserve, (notification) => {
	Console.WriteLine ($"Observed DidUpdateNotification for {nameof (objectToObserve)}!");
};

// Stop listening for notifications
token.Dispose ();