NSPersistentStoreCoordinator.StoresWillChangeNotification 属性

定义

命名空间:

CoreData

程序集:

Xamarin.iOS.dll

StoresWillChange 的通知常量

[Foundation.Advice("Use NSPersistentStoreCoordinator.Notifications.ObserveStoresWillChange helper method instead.")]
[Foundation.Field("NSPersistentStoreCoordinatorStoresWillChangeNotification", "CoreData")]
[ObjCRuntime.Introduced(ObjCRuntime.PlatformName.iOS, 7, 0, ObjCRuntime.PlatformArchitecture.All, null)]
[ObjCRuntime.Introduced(ObjCRuntime.PlatformName.MacOSX, 10, 9, ObjCRuntime.PlatformArchitecture.All, null)]
public static Foundation.NSString StoresWillChangeNotification { [ObjCRuntime.Introduced(ObjCRuntime.PlatformName.iOS, 7, 0, ObjCRuntime.PlatformArchitecture.All, null)] [ObjCRuntime.Introduced(ObjCRuntime.PlatformName.MacOSX, 10, 9, ObjCRuntime.PlatformArchitecture.All, null)] get; }

member this.StoresWillChangeNotification : Foundation.NSString

属性值

NSString

NSString 常量 应用作 NSNotificationCenter 的标记。

属性

AdviceAttribute FieldAttribute IntroducedAttribute

注解

此常量可用于注册 NSNotificationCenter 此通知的侦听器。 这是 NSString 而不是字符串，因为这些值可以用作某些本机库中的标记，而不是纯粹用于其实际字符串内容。 回调的“notification”参数包含特定于通知类型的额外信息。

若要订阅此通知，开发人员可以使用便捷 NSPersistentStoreCoordinator.Notifications的 .ObserveStoresWillChange 方法，该方法提供对通知参数的强类型访问。

以下示例演示如何使用强类型 Notifications 类来排除通知中可用属性的猜测：

//
// Lambda style
//

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

    Console.WriteLine ("EventType", args.EventType);
});

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

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

    Console.WriteLine ("EventType", args.EventType);
}

void Setup ()
{
    notification = NSPersistentStoreCoordinator.Notifications.ObserveStoresWillChange (Callback);
}

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

以下示例演示如何将通知与 DefaultCenter API 配合使用：

// Lambda style
NSNotificationCenter.DefaultCenter.AddObserver (
        NSPersistentStoreCoordinator.StoresWillChangeNotification, (notification) => {Console.WriteLine ("Received the notification NSPersistentStoreCoordinator", notification); }


// Method style
void Callback (NSNotification notification)
{
    Console.WriteLine ("Received a notification NSPersistentStoreCoordinator", notification);
}

void Setup ()
{
    NSNotificationCenter.DefaultCenter.AddObserver (NSPersistentStoreCoordinator.StoresWillChangeNotification, Callback);
}