AVCaptureDevice.Notifications.ObserveSubjectAreaDidChange Method

Definition

Namespace:

AVFoundation

Assembly:

Xamarin.iOS.dll

Overloads

ObserveSubjectAreaDidChange(EventHandler<NSNotificationEventArgs>)	Strongly typed notification for the SubjectAreaDidChangeNotification constant.
ObserveSubjectAreaDidChange(NSObject, EventHandler<NSNotificationEventArgs>)	Strongly typed notification for the SubjectAreaDidChangeNotification constant.

ObserveSubjectAreaDidChange(EventHandler<NSNotificationEventArgs>)

Strongly typed notification for the SubjectAreaDidChangeNotification constant.

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

static member ObserveSubjectAreaDidChange : 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 = AVCaptureDevice.Notifications.ObserveSubjectAreaDidChange ((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 = AVCaptureDevice.Notifications.ObserveSubjectAreaDidChange (Callback);
}

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

ObserveSubjectAreaDidChange(NSObject, EventHandler<NSNotificationEventArgs>)

Strongly typed notification for the SubjectAreaDidChangeNotification constant.

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

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

Parameters

objectToObserve

NSObject

The specific object to observe.

handler

EventHandler<NSNotificationEventArgs>

The handler that responds to the notification when it occurs.

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 SubjectAreaDidChangeNotification notifications.

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

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

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