iOS 正则 检测是否为手机号

- (BOOL)validateMobile:(NSString *)mobileNum
{
    NSString *regex = @"^1[3|5|7|8][0-9]\\d{8}$";
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];

    if(![pred evaluateWithObject:mobileNum])
    {
        return NO;
    }

    else
    {
        return YES;
    }
}

是手机号，返回YES，不是手机号，返回NO