MessageReceivedHandler Delegate

Definition

Namespace:

Windows.Networking.Proximity

Describes the method that will handle the event that's fired when a message that has been subscribed to has been received.

public delegate void MessageReceivedHandler(ProximityDevice ^ sender, ProximityMessage ^ message);

/// [Windows.Foundation.Metadata.ContractVersion(Windows.Foundation.UniversalApiContract, 65536)]
/// [Windows.Foundation.Metadata.Guid(4020963202, 63202, 18037, 160, 69, 216, 227, 32, 194, 72, 8)]
class MessageReceivedHandler : MulticastDelegate

[Windows.Foundation.Metadata.ContractVersion(typeof(Windows.Foundation.UniversalApiContract), 65536)]
[Windows.Foundation.Metadata.Guid(4020963202, 63202, 18037, 160, 69, 216, 227, 32, 194, 72, 8)]
public delegate void MessageReceivedHandler(ProximityDevice sender, ProximityMessage message);

var messageReceivedHandlerHandler = function(sender, message){
/* Your code */
}

Public Delegate Sub MessageReceivedHandler(sender As ProximityDevice, message As ProximityMessage)

Parameters

sender

ProximityDevice

The proximity device that received the message.

message

ProximityMessage

The message and related data that were passed to the event handler.

Attributes

ContractVersionAttribute GuidAttribute

Windows requirements

Device family	Windows 10 (introduced in 10.0.10240.0 - for Xbox, see UWP features that aren't yet supported on Xbox)
API contract	Windows.Foundation.UniversalApiContract (introduced in v1.0)
App capabilities	ID_CAP_PROXIMITY [Windows Phone] proximity ID_CAP_PROXIMITY [Windows Phone]

Examples

Windows.Networking.Proximity.ProximityDevice proximityDevice;
long publishedMessageId = -1;
long subscribedMessageId = -1;

private void initializeProximityDevice()
{
    proximityDevice = Windows.Networking.Proximity.ProximityDevice.GetDefault();

    if (proximityDevice != null)
    {
        PublishMessageButton.Click += PublishMessage;
        SubscribeForMessageButton.Click += SubscribeForMessage;
        StopSubscribingForMessageButton.Click += StopSubscribingForMessage;
        StopPublishingMessageButton.Click += StopPublishingMessage;
    }
    else
    {
        WriteMessageText("Failed to initialized proximity device.\n");
    }
}

private void PublishMessage(object sender, RoutedEventArgs e)
{
    // Stop publishing the current message.
    if (publishedMessageId != -1)
    {
        proximityDevice.StopPublishingMessage(publishedMessageId);
    }

    publishedMessageId = 
        proximityDevice.PublishMessage("Windows.SampleMessage", MessageTextBlock.Text);
}

private void SubscribeForMessage(object sender, RoutedEventArgs e)
{
    // Only subscribe for the message one time.
    if (subscribedMessageId == -1)
    {
        subscribedMessageId = 
        proximityDevice.SubscribeForMessage("Windows.SampleMessage", messageReceived);
    }
}

private void messageReceived(
    Windows.Networking.Proximity.ProximityDevice device, 
    Windows.Networking.Proximity.ProximityMessage message)
{
    MessageBlock.Text += "Message received: " + message.DataAsString + "\n";
}

private void StopSubscribingForMessage(object sender, RoutedEventArgs e)
{
    proximityDevice.StopSubscribingForMessage(subscribedMessageId);
    subscribedMessageId = -1;
}

private void StopPublishingMessage(object sender, RoutedEventArgs e)
{
    proximityDevice.StopPublishingMessage(publishedMessageId);
    publishedMessageId = -1;
}

// Write a message to MessageBlock on the UI thread.
private Windows.UI.Core.CoreDispatcher messageDispatcher = Window.Current.CoreWindow.Dispatcher;

async private void WriteMessageText(string message, bool overwrite = false)
{
    await messageDispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
        () =>
        {
            if (overwrite)
                MessageBlock.Text = message;
            else
                MessageBlock.Text += message;
        });
}

Private proximityDevice As Windows.Networking.Proximity.ProximityDevice
Private publishedMessageId As Long = -1
Private subscribedMessageId As Long = -1

Private Sub initializeProximityDevice()
    proximityDevice = Windows.Networking.Proximity.ProximityDevice.GetDefault()

    If proximityDevice IsNot Nothing Then
        AddHandler PublishMessageButton.Click, AddressOf PublishMessage
        AddHandler SubscribeForMessageButton.Click, AddressOf SubscribeForMessage
        AddHandler StopSubscribingForMessageButton.Click, AddressOf StopSubscribingForMessage
        AddHandler StopPublishingMessageButton.Click, AddressOf StopPublishingMessage
    Else
        WriteMessageText("Failed to initialized proximity device." & vbTab)
    End If
End Sub

Private Sub PublishMessage(sender As Object, e As RoutedEventArgs)
    ' Stop publishing the current message.
    If publishedMessageId <> -1 Then
        proximityDevice.StopPublishingMessage(publishedMessageId)
    End If

    publishedMessageId =
        proximityDevice.PublishMessage("Windows.SampleMessage", MessageTextBlock.Text)
End Sub

Private Sub SubscribeForMessage(sender As Object, e As RoutedEventArgs)
    ' Only subscribe for the message one time.
    If subscribedMessageId = -1 Then
        subscribedMessageId =
        proximityDevice.SubscribeForMessage("Windows.SampleMessage", AddressOf messageReceived)
    End If
End Sub

Private Sub messageReceived(
    device As Windows.Networking.Proximity.ProximityDevice,
    message As Windows.Networking.Proximity.ProximityMessage)

    MessageBlock.Text &= "Message received: " & message.DataAsString & vbTab
End Sub

Private Sub StopSubscribingForMessage(sender As Object, e As RoutedEventArgs)
    proximityDevice.StopSubscribingForMessage(subscribedMessageId)
    subscribedMessageId = -1
End Sub

Private Sub StopPublishingMessage(sender As Object, e As RoutedEventArgs)
    proximityDevice.StopPublishingMessage(publishedMessageId)
    publishedMessageId = -1
End Sub

' Write a message to MessageBlock on the UI thread.
Private Async Sub WriteMessageText(message As String, Optional overwrite As Boolean = False)
    Await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
        Sub()
            If overwrite Then
                MessageBlock.Text = message
            Else
                MessageBlock.Text &= message
            End If
        End Sub)
End Sub

See also

• SubscribeForMessage(String, MessageReceivedHandler)
• Proximity and Tapping (C#/VB/C++)
• Proximity sample