- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{    if ([textField.text isEqualToString:@"0"] &&        string.length)    {        if (![string isEqualToString:@"."])        {            return NO;        }        else        {            return YES;        }    }        NSString *tmpString = [textField.text stringByAppendingString:string];        if (![tmpString isNumber] && string.length)    {        if ([tmpString isFloatValue_fs])        {            return YES;        }                return NO;    }        return YES;}