ios - method works n times before playing card game, fails first time afterwards -

i don't know how title question, apologies in advance....

building flash card app. deck of cards can filtered through preferences include/exclude continents. set filter include 1 continent, play game successfully. after finishing deck, decide include second continent. fail.

i'm using tableviewcontroller display 6 continents. prototype cell "right detail". textlabel.text continent name. detailtext.text shows inclusion/exclusion state.

all continents start "include". click on row, toggles on/off.

i can make changes on screen, save settings, come , make more changes without crashing. app only crashes after going through deck 1 time, 10 cards or 100.

error message: -[__nsarrayi addobject:]: unrecognized selector sent instance

-(void)tableview:(uitableview *)tableview didselectrowatindexpath:(nsindexpath *)indexpath { uitableviewcell *cell = [tableview cellforrowatindexpath:indexpath]; nsstring *name = cell.textlabel.text; if ([[gamesettingsobject sharedinstance].chosencontinents containsobject:name]) {     if ([[gamesettingsobject sharedinstance].chosencontinents count]>1) {         [[gamesettingsobject sharedinstance].chosencontinents removeobject:name];         cell.detailtextlabel.text = @"exclude";     } } else {     [[gamesettingsobject sharedinstance].chosencontinents addobject:name];     cell.detailtextlabel.text = @"include"; } 

}

any ideas?

you can add objects mutable array. think array becomes nsarray somehow. check that.