PeerWatcher.Updated Event

Definition

Namespace:

Windows.Networking.Proximity

Occurs when the DisplayName or DiscoveryData for a peer app within wireless range has changed.

// Register
event_token Updated(TypedEventHandler<PeerWatcher, PeerInformation const&> const& handler) const;

// Revoke with event_token
void Updated(event_token const* cookie) const;

// Revoke with event_revoker
PeerWatcher::Updated_revoker Updated(auto_revoke_t, TypedEventHandler<PeerWatcher, PeerInformation const&> const& handler) const;

public event TypedEventHandler<PeerWatcher,PeerInformation> Updated;

function onUpdated(eventArgs) { /* Your code */ }
peerWatcher.addEventListener("updated", onUpdated);
peerWatcher.removeEventListener("updated", onUpdated);
- or -
peerWatcher.onupdated = onUpdated;

Public Custom Event Updated As TypedEventHandler(Of PeerWatcher, PeerInformation) 

Event Type

TypedEventHandler<PeerWatcher,PeerInformation>

Windows requirements

App capabilities

proximity

Remarks

The Updated event is raised when the DisplayName or DiscoveryData for a peer app changes. You can use the Id property to uniquely identify the peer app and update your UI.

Important

For Windows Phone 8.x apps, calling PeerFinder.ConnectAsync from within an Updated event handler will fail. Instead, call it outside of this event handler, for example, when the user has explicitly chosen to connect to a peer.

private PeerWatcher _peerWatcher;
private bool _peerWatcherIsRunning = false;
private bool _peerFinderStarted = false;

// The list of peers discovered by the PeerWatcher.
ObservableCollection<PeerInformation> _discoveredPeers = new ObservableCollection<PeerInformation>();
void PeerFinder_StartPeerWatcher(object sender, RoutedEventArgs e)
{
    if (!_peerFinderStarted)
    {
        // PeerFinder must be started first.
        return;
    }

    if (_peerWatcherIsRunning)
    {
        // PeerWatcher is already running.
        return;
    }

    try
    {
        if (_peerWatcher == null)
        {
            _peerWatcher = PeerFinder.CreateWatcher();

            // Add PeerWatcher event handlers. Only add handlers once.
            _peerWatcher.Added += PeerWatcher_Added;
            _peerWatcher.Removed += PeerWatcher_Removed;
            _peerWatcher.Updated += PeerWatcher_Updated;
            _peerWatcher.EnumerationCompleted += PeerWatcher_EnumerationCompleted;
            _peerWatcher.Stopped += PeerWatcher_Stopped;
        }

        // Empty the list of discovered peers.
        _discoveredPeers.Clear();

        // Start the PeerWatcher.
        _peerWatcher.Start();

        _peerWatcherIsRunning = true;
    }
    catch (Exception ex)
    {
        // Exceptions can occur if PeerWatcher.Start is called multiple times or
        // PeerWatcher.Start is called the PeerWatcher is stopping.
    }
}

protected override void OnNavigatingFrom(NavigatingCancelEventArgs e)
{
    if (_peerWatcher != null)
    {
        // Remove event handlers.
        _peerWatcher.Added -= PeerWatcher_Added;
        _peerWatcher.Removed -= PeerWatcher_Removed;
        _peerWatcher.Updated -= PeerWatcher_Updated;
        _peerWatcher.EnumerationCompleted -= PeerWatcher_EnumerationCompleted;
        _peerWatcher.Stopped -= PeerWatcher_Stopped;

        _peerWatcher = null;
    }
}

private void PeerWatcher_Updated(PeerWatcher sender, PeerInformation peerInfo)
{
    var ignored = Dispatcher.RunAsync(CoreDispatcherPriority.Low, () =>
    {
        lock (this)
        {
            // Find and update the peer in the list of discovered peers.
            for (int i = 0; i < _discoveredPeers.Count; i++)
            {
                if (_discoveredPeers[i].Id == peerInfo.Id)
                {
                    _discoveredPeers[i] = peerInfo;
                }
            }
        }
    });
}

See also

• Proximity and Tapping (C#/VB/C++)
• Proximity sample