PeerFinder.CreateWatcher Method

Reference

Definition

Namespace:: Windows.Networking.Proximity

Important

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Edit

Creates a new instance of a PeerWatcher object for dynamic discovery of peer apps.

public:
 static PeerWatcher ^ CreateWatcher();

 static PeerWatcher CreateWatcher();

public static PeerWatcher CreateWatcher();

function createWatcher()

Public Shared Function CreateWatcher () As PeerWatcher

Returns

PeerWatcher

An instance of a PeerWatcher object for dynamic discovery of peer apps.

Windows requirements

App capabilities

proximity

Remarks

You must first call the Start method before calling the CreateWatcher method.

If you call the CreateWatcher method multiple times, you will receive a reference to the same PeerWatcher instance.

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;
    }
}

Applies to