public void removeObserver(System.Object target){
Dictionary<string ,List<NSNotificationObserver>> name_observers_copy = new Dictionary<string, List<NSNotificationObserver>> (_name_observers);
var enumerator = name_observers_copy.GetEnumerator();
while (enumerator.MoveNext()) {
KeyValuePair<string ,List<NSNotificationObserver>> keyValuePair = enumerator.Current;
List<NSNotificationObserver> observers = keyValuePair.Value;
observers.RemoveAll(observer=>observer.target==target);
if(observers.Count==0){
_name_observers.Remove(keyValuePair.Key);
}
}
}
public void removeObserver(System.Object target, string name){
