AVCaptureDevice.Notifications.ObserveSubjectAreaDidChange 方法

定义

重载

ObserveSubjectAreaDidChange(EventHandler<NSNotificationEventArgs>)

常量的强类型通知 SubjectAreaDidChangeNotification

ObserveSubjectAreaDidChange(NSObject, EventHandler<NSNotificationEventArgs>)

常量的强类型通知 SubjectAreaDidChangeNotification

ObserveSubjectAreaDidChange(EventHandler<NSNotificationEventArgs>)

常量的强类型通知 SubjectAreaDidChangeNotification

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

参数

handler
EventHandler<NSNotificationEventArgs>

发布通知时调用的方法。

返回

令牌对象,可用于通过释放通知或将其传递给来停止接收通知 RemoveObservers(IEnumerable<NSObject>)

注解

以下示例演示如何在代码中使用此方法

//
// 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 ();
}

适用于

ObserveSubjectAreaDidChange(NSObject, EventHandler<NSNotificationEventArgs>)

常量的强类型通知 SubjectAreaDidChangeNotification

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

参数

objectToObserve
NSObject

要观察的特定对象。

handler
EventHandler<NSNotificationEventArgs>

发生通知时响应通知的处理程序。

返回

令牌对象,可用于通过释放通知或将其传递给来停止接收通知 RemoveObservers(IEnumerable<NSObject>)

注解

此方法可用于订阅 SubjectAreaDidChangeNotification 通知。

// 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 ();

适用于