AVCaptureDevice.Notifications.ObserveSubjectAreaDidChange 方法
定义
重要
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重载
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 ();