NSManagedObjectContext.Notifications.ObserveWillSave 方法

定义

命名空间:

CoreData

程序集:

Xamarin.iOS.dll

重载

ObserveWillSave(EventHandler<NSNotificationEventArgs>)	常量的强类型通知 WillSaveNotification 。
ObserveWillSave(NSObject, EventHandler<NSNotificationEventArgs>)	常量的强类型通知 WillSaveNotification 。

ObserveWillSave(EventHandler<NSNotificationEventArgs>)

常量的强类型通知 WillSaveNotification 。

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

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

参数

handler

EventHandler<NSNotificationEventArgs>

发布通知时调用的方法。

返回

NSObject

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 = NSManagedObjectContext.Notifications.ObserveWillSave ((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 = NSManagedObjectContext.Notifications.ObserveWillSave (Callback);
}

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

ObserveWillSave(NSObject, EventHandler<NSNotificationEventArgs>)

常量的强类型通知 WillSaveNotification 。

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

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

参数

objectToObserve

NSObject

要观察的对象。

handler

EventHandler<NSNotificationEventArgs>

发布通知时调用的方法。

返回

NSObject

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 WillSaveNotification 通知。

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

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

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