idealised conceptual iOS python app. again (not complete)

app.py

import pyios
import helpers
from boxcore import Session, Playlist

class BoxListView(pyios.TableView):
    def __init__(self,session):
        super(BoxListView,self).__init__(self)        
        self.session = session
        self.title = "Box Play"
        self.show_edit_button = True
        self.left_buttons = [pyios.Navigation.SystemButton("add",handler=self.plus_button)]

    def plus_button(self,sender):
        title = pyios.InputBox("New Box",placeholder="Title",ok="Save")
        if title:
            playlist = self.session.add_playlist(title)
            self.insert_row(-1,animation="slide_bottom")
            self.show_playlist(playlist,new=True)        

    @pyios.TableView.CellClass("playlist_cell")
    def playlist_cell(self):
        return pyios.TableViewCell(pyios.TableViewCell.StyleDetail)        

    def get_cell(self,section,index):
        playlist = self.session.playlists[index]
        cell = self.deque_cell("playlist_cell")
        cell.text_label.text = playlist.title
        cell.detail_text_label.text = helpers.pluralize("song",len(playlist.entries))
        return cell

class BoxPlayApp(pyios.App):
    def on_app_start(self,url,file_open):
        self.session = Session.load_session()
        self.window = pyios.MainWindow()
        self.window.add_subview(BoxListView(session))
        self.window.show()