PeerWatcher.Removed Event

Reference

Definition

Namespace:: Windows.Networking.Proximity

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Edit

Occurs when a peer app is no longer within wireless range.

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

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

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

public event TypedEventHandler<PeerWatcher,PeerInformation> Removed;

function onRemoved(eventArgs) { /* Your code */ }
peerWatcher.addEventListener("removed", onRemoved);
peerWatcher.removeEventListener("removed", onRemoved);
- or -
peerWatcher.onremoved = onRemoved;

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

Event Type

TypedEventHandler<PeerWatcher,PeerInformation>

Windows requirements

App capabilities

proximity

Remarks

The Removed event is raised when a peer app is removed from the collection of enumerated peer apps. This may happen if a user switches apps or if a device is no longer within range.

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_Removed(PeerWatcher sender, PeerInformation peerInfo)
{
    var result = Dispatcher.RunAsync(CoreDispatcherPriority.Low, () =>
    {
        lock (this)
        {
            // Find and remove the peer form the list of discovered peers.
            for (int i = 0; i < _discoveredPeers.Count; i++)
            {
                if (_discoveredPeers[i].Id == peerInfo.Id)
                {
                    _discoveredPeers.RemoveAt(i);
                }
            }
        }
    });
}

Applies to