Determine if the bank account is entered correctly

Do not say  the direct sticker code   to enter the bank card number can be judged

-(void) viewdidload {    [super viewdidload];    NSString *str = @ "6226820011200783033";    BOOL isright = [self checkcardno:str];    if (!isright) {                Uialertview *alert = [[Uialertview alloc]initwithtitle:@ ' not ' message:@ ' please reenter card number ' Delegate:nil Cancelbuttontitle:nil Otherbuttontitles:nil, nil];        [Alert show];    } else{        Uialertview *alert = [[Uialertview alloc]initwithtitle:@ "to" message:@ "" Delegate:nil CancelButtonTitle:nil Otherbuttontitles:nil, nil];        [Alert show];}}

That's the way to judge.

-(BOOL) Checkcardno: (nsstring*) cardno{int oddsum = 0;    Odd sum int evensum = 0;    even sum int allsum = 0;    int cardnolength = (int) [Cardno length];        int lastnum = [[Cardno substringfromindex:cardnolength-1] intvalue];    Cardno = [Cardno substringtoindex:cardnolength-1]; for (int i = cardNoLength-1; i>=1;i--) {NSString *tmpstring = [Cardno substringwithrange:nsmakerange (I-1, 1)]        ;        int tmpval = [tmpstring intvalue];                if (cardnolength% 2 ==1) {if ((i% 2) = = 0) {tmpval *= 2;                if (tmpval>=10) tmpval-= 9;            Evensum + = Tmpval;            }else{oddsum + = Tmpval;                }}else{if ((i% 2) = = 1) {Tmpval *= 2;                if (tmpval>=10) tmpval-= 9;            Evensum + = Tmpval;            }else{oddsum + = Tmpval; }}} allsum = Oddsum + EvensuM    Allsum + = Lastnum;    if ((allsum%) = = 0) return YES; else return NO;}

Determine if the bank account is entered correctly