关于钱的数字校验

第一种

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    NSString *result = [textField.text stringByReplacingCharactersInRange:range withString:string];
    if (result.length == 0) {
        return YES;
    }
    return [self isValidNumber:result];
}

- (BOOL)isValidNumber:(NSString *) numberStr {
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", @"^\\d{1,12}((?:\\.\\d{1,2})|\\.)?$"];
    if (![predicate evaluateWithObject:numberStr]) {
        return NO;
    }
    return YES;
}

第二种

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    if ([textField.text rangeOfString:@"."].location == NSNotFound) {
        isHaveDian = NO;
    }
    if ([string length] > 0) {
        unichar single = [string characterAtIndex:0];//当前输入的字符
        if ((single >= '0' && single <= '9') || single == '.') { //数据格式正确
            //首字母不能为0和小数点
            if ([textField.text length] == 0) {
                if(single == '.') {
//                    [self showError:@"亲，第一个数字不能为小数点"];
                    [textField.text stringByReplacingCharactersInRange:range withString:@""];
                    return NO;
                }
                if (single == '0') {
//                    [self showError:@"亲，第一个数字不能为0"];
                    [textField.text stringByReplacingCharactersInRange:range withString:@""];
                    return NO;
                }
            }

            //输入的字符是否是小数点
            if (single == '.') {
                if(!isHaveDian) { //text中还没有小数点
                    isHaveDian = YES;
                    return YES;
                } else {
//                    [self showError:@"亲，您已经输入过小数点了"];
                    [textField.text stringByReplacingCharactersInRange:range withString:@""];
                    return NO;
                }
            } else {
                if (isHaveDian) {//存在小数点
                    //判断小数点的位数
                    NSRange ran = [textField.text rangeOfString:@"."];
                    if (range.location - ran.location <= 2) {
                        return YES;
                    }else{
//                        [self showError:@"亲，您最多输入两位小数"];
                        return NO;
                    }
                } else {
                    return YES;
                }
            }
        } else {//输入的数据格式不正确
//            [self showError:@"亲，您输入的格式不正确"];
            [textField.text stringByReplacingCharactersInRange:range withString:@""];
            return NO;
        }
    }
    else {
        return YES;
    }
}