public CFNotificationObserverToken AddObserver(string name, INativeObject objectToObserve, Action <string, NSDictionary> notificationHandler,
CFNotificationSuspensionBehavior suspensionBehavior = CFNotificationSuspensionBehavior.DeliverImmediately)
{
if (darwinnc != null && darwinnc.Handle == Handle)
{
if (name == null)
{
throw new ArgumentNullException("name", "When using the Darwin Notification Center, the value passed must not be null");
}
}
var strHandle = name == null ? IntPtr.Zero : NSString.CreateNative(name);
name = name ?? NullNotificationName;
var token = new CFNotificationObserverToken()
{
stringName = name,
centerHandle = handle,
nameHandle = strHandle,
observedObject = objectToObserve == null ? IntPtr.Zero : objectToObserve.Handle,
listener = notificationHandler
};
//
// To allow callbacks to add observers, we duplicate the list of listeners on AddObserver
// We do the duplication on AddObserver, instead of making a copy on the notification
// callback, as we expect the notification callback to be a more common operation
// than the AddObserver operation
//
List <CFNotificationObserverToken> listenersForName;
lock (listeners){
if (!listeners.TryGetValue(name, out listenersForName))
{
listenersForName = new List <CFNotificationObserverToken> (1);
CFNotificationCenterAddObserver(center: handle,
observer: handle,
callback: NotificationCallback,
name: strHandle,
obj: token.observedObject,
suspensionBehavior: (IntPtr)suspensionBehavior);
}
else
{
listenersForName = new List <CFNotificationObserverToken> (listenersForName);
}
listenersForName.Add(token);
listeners [name] = listenersForName;
}
return(token);
}
public void RemoveObserver(CFNotificationObserverToken token)
{
if (token == null)
{
throw new ArgumentNullException("token");
}
if (token.nameHandle == IntPtr.Zero && token.stringName != NullNotificationName)
{
throw new ObjectDisposedException("token");
}
if (token.centerHandle != handle)
{
throw new ArgumentException("token", "This token belongs to a different notification center");
}
lock (listeners){
var list = listeners [token.stringName];
List <CFNotificationObserverToken> newList = null;
foreach (var e in list)
{
if (e == token)
{
continue;
}
if (newList == null)
{
newList = new List <CFNotificationObserverToken> ();
}
newList.Add(e);
}
if (newList != null)
{
listeners [token.stringName] = newList;
return;
}
else
{
listeners.Remove(token.stringName);
}
}
CFNotificationCenterRemoveObserver(handle, this.Handle, name: token.nameHandle, obj: token.observedObject);
NSString.ReleaseNative(token.nameHandle);
token.nameHandle = IntPtr.Zero;
}