Swift仅显示已过去的日期

Question

我正在从Firebase检索包含日期的数据。我只想显示日期已经过去的项目。目前显示日期是否已经过了日期，例如，如果日期是25/02/17，那么26日及之后的日期将不显示，但是日期低于25日将尽管月份是什么。那么如何才能让它考虑到月份和年份呢？

以下是我目前的代码。

   func setupAgendaData() {
    var ref: FIRDatabaseReference!
    ref = FIRDatabase.database().reference()
    let userID = FIRAuth.auth()?.currentUser?.uid
    print(userID)
    ref.child("users").child(userID!).child("Agenda").observeEventType(.Value, withBlock: { (snapshot) in
        self.agenda.removeAll()
        print(snapshot)
        for item in snapshot.children.allObjects as! [FIRDataSnapshot] {

            if let dictionary = item.value as? [String: AnyObject] {
                let agendaItem = Agenda()
                agendaItem.setValuesForKeysWithDictionary(dictionary)
                self.agenda.append(agendaItem)

            }
        }
        dispatch_async(dispatch_get_main_queue(), {
            self.collectionView.reloadData()

        })

    }) { (error) in
        print(error.localizedDescription)
    }
    }


func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

 /*   let actDate = ActDate()
    let date = NSDate()
    let dateFormatter = NSDateFormatter()
    dateFormatter.dateFormat = "dd/MM/yy"
    actDate.date = dateFormatter.stringFromDate(date)

    //if self.agenda < actDate.date {
        print(agenda.count)
  //  }
   print(agenda.count)
 */
  return agenda.count
   }


func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let previousCell = collectionView.dequeueReusableCellWithReuseIdentifier(previousCellId, forIndexPath: indexPath) as! PreviousCell

    let actDate = ActDate()
    let date = NSDate()
    let dateFormatter = NSDateFormatter()
    dateFormatter.dateFormat = "dd/MM/yy"
    actDate.date = dateFormatter.stringFromDate(date)

    let filtAgenda = agenda[indexPath.item].date < actDate.date
    if filtAgenda == true {

    previousCell.nameLabel.text = agenda[indexPath.item].activity
    previousCell.timeLabel.text = agenda[indexPath.item].time
    previousCell.dateLabel.text = agenda[indexPath.item].date

    }


    return previousCell

    }