Skip to main content
PeerFinder.CreateWatcher | createWatcher method

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

Syntax


var peerWatcher = Windows.Networking.Proximity.PeerFinder.createWatcher();

public static PeerWatcher CreateWatcher()

Public Shared Function CreateWatcher() As PeerWatcher

public:
static PeerWatcher^ CreateWatcher()

Parameters

This method has no parameters.

Return value

Type: PeerWatcher

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

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;
    }
}

var _peerWatcher;
var _peerWatcherIsRunning = false;
var _peerFinderStarted = false;

// The list of peers discovered by the PeerWatcher.
var _discoveredPeers = new Array();

function peerFinder_StartPeerWatcher() {
    if (!_peerFinderStarted) {
        // PeerFinder must be started first.
       return;
    }

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

    try {
        if (!_peerWatcher)
        {
            _peerWatcher = PeerFinder.createWatcher();

            // Add PeerWatcher event handlers. Only add handlers once.
            peerWatcher.addEventListener("added", peerWatcher_Added); 
            peerWatcher.addEventListener("removed", peerWatcher_Removed); 
            peerWatcher.addEventListener("updated",  peerWatcher_Updated); 
            peerWatcher.addEventListener("enumerationcompleted", peerWatcher_EnumerationCompleted); 
            peerWatcher.addEventListener("stopped", peerWatcher_Stopped); 
        }

        // Empty the list of discovered peers.
        _discoveredPeers = new Array();

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

        _peerWatcherIsRunning = true;
    }
    catch (ex)
    {
        // Exceptions can occur if PeerWatcher.Start is called multiple times or
        // PeerWatcher.Start is called the PeerWatcher is stopping.
    }
}
    
function cleanup() {
    if (_peerWatcher) {
        // Remove event handlers.
        peerWatcher.removeEventListener("added", peerWatcher_Added); 
        peerWatcher.removeEventListener("removed", peerWatcher_Removed); 
        peerWatcher.removeEventListener("updated", peerWatcher_Updated); 
        peerWatcher.removeEventListener("enumerationCompleted", peerWatcher_EnumerationCompleted); 
        peerWatcher.removeEventListener("stopped", peerWatcher_Stopped); 

        _peerWatcher = null;
    }
}

Requirements (Windows 10 device family)

Device family

Universal, introduced version 10.0.10240.0 [for Xbox, see UWP features that aren't yet supported on Xbox]

API contract

Windows.Foundation.UniversalApiContract, introduced version 1.0

Namespace

Windows.Networking.Proximity
Windows::Networking::Proximity [C++]

Metadata

Windows.Foundation.UniversalApiContract.winmd

Requirements (Windows 8.x and Windows Phone 8.x)

Minimum supported client

Windows 8.1

Minimum supported server

Windows Server 2012 R2

Minimum supported phone

Windows Phone 8.1 [Windows Phone Silverlight 8.1 and Windows Runtime apps]

Namespace

Windows.Networking.Proximity
Windows::Networking::Proximity [C++]

Metadata

Windows.winmd

See also

PeerFinder
Proximity and Tapping (JavaScript)
Proximity and Tapping (C#/VB/C++)
Samples
Proximity sample