ios - use uidatepicker to set textfield value -

i have uidatepicker stores date selected textfield. want text field calculates how old person (as whole int) depending on date entered, e.g. "15". unsure how that. point me in right direction please . here's have far.

-(void)viewdidappear:(bool)animated{     [birthdaydatepicker addtarget:self                    action:@selector(datechanged:)          forcontrolevents:uicontroleventvaluechanged]; }  - (void) datechanged:(id)sender{     nsdateformatter *dateformatter = [[nsdateformatter alloc] init];     dateformatter.datestyle = nsdateformatterlongstyle;     birthdaytextfield.text = [nsstring stringwithformat:@"%@",                    [dateformatter stringfromdate:birthdaydatepicker.date]];     //look @ todays date, subtract date in birthdaytextfield calculate age maybe?  } 

you can try this

- (void) datechanged:(id)sender{     nsdateformatter *dateformatter = [[nsdateformatter alloc] init];     [dateformatter setdateformat:@"yyyy-mm-dd hh:mm:ss"];     nsstring *startdate= [nsstring stringwithformat:@"%@",                               [dateformatter stringfromdate: birthdaydatepicker.date]];      nsdate *end=[dateformatter datefromstring:[dateformatter stringfromdate:[nsdate date]]];      nscalendar *gregoriancalendar = [[nscalendar alloc] initwithcalendaridentifier:nsgregoriancalendar];     nsdatecomponents *components = [gregoriancalendar components:nsyearcalendarunit                                                         fromdate:[dateformatter datefromstring:startdate]                                                           todate:end                                                          options:0];  birthdaytextfield.text=[nsstring stringwithformat:@" %d years old",components.year];  }