ios - NSDecimalNumber, addition, and just not sure -

I'm not sure what to do next. They are only dollar amount from a text field. I am trying. NSString * checkAmount = [checkAmountInput.text substringFromIndex: 1]; NSDecimalNumber * checkAmountValue = (NSDecimalNumber *) [NSString stringWithFormat: @ "% @", checkAmain]; NSLog (@ "% @", check Amount Value); NSST * Bank Balance = [Bank Balance Input. Substitution Form Index: 1]; NSDecimalNumber * Bank Balance Value = (NSDecimalNumber *) [NSString stringWithFormat: @ "% @", Bank Balance]; NSLog (@ "% @", Bank Balance Value); NSDecimalNumber * totalAmount = NSLog (@ "% @", total amount);

When I try to use the decimal number, then I add:

  '- [__ NSCF string desemban decimal bending:]: unrecognized selector For example, 0x8a39a10 '  
 It may be that I am going about all this wrong ... but I am starting again now.   
 
 
 your  checkout value  and  bank balance value  Actually casting  NSDecimalNumber  not  NSString  to a  NSDecimalNumber  will compromise a compiler warning, but the objects are still string.  
 You can create an example from a string:  
  NSString * bankBalance =  
  
 [BankBalanceInput.text substringFromIndex: 1]; NSDCCNumber * Bank Balance Value = [NSDCilanmar Decimal Decimal Number: Bank Balance];