判断邮箱是否合法的代码

http://www.devdiv.com/home.php?mod=space&uid=8639&do=blog&id=4090
//判断邮箱是否合法的代码
-(BOOL)validateEmail:(NSString*)email
{
    if((0 != [email rangeOfString:@"@"].length) &&
         (0 != [email rangeOfString:@"."].length))
    {
          
           NSCharacterSet* tmpInvalidCharSet = [[NSCharacterSet alphanumericCharacterSet] invertedSet];
        NSMutableCharacterSet* tmpInvalidMutableCharSet = [[tmpInvalidCharSet mutableCopy] autorelease];
        [tmpInvalidMutableCharSet removeCharactersInString:@"_-"];
       
           //使用compare option 来设定比较规则，如
           //NSCaseInsensitiveSearch是不区分大小写
           //NSLiteralSearch 进行完全比较,区分大小写
           //NSNumericSearch 只比较定符串的个数，而不比较字符串的字面值
        NSRange range1 = [email rangeOfString:@"@"
                                              optio n s:NSCaseInsensitiveSearch];
       
        //取得用户名部分
        NSString* userNameString = [email substringToIndex:range1.location];
        NSArray* userNameArray   = [userNameString componentsSeparatedByString:@"."];
          
        for(NSString* string in userNameArray)
           {
            NSRange rangeOfInavlidChars = [string rangeOfCharacterFromSet: tmpInvalidMutableCharSet];
            if(rangeOfInavlidChars.length != 0 || [string isEqualToString:@""])
                return NO;
        }
       
        NSString *domainString = [email substringFromIndex:range1.location+1];
        NSArray *domainArray   = [domainString componentsSeparatedByString:@"."];
       
        for(NSString *string in domainArray)
           {
            NSRange rangeOfInavlidChars=[string rangeOfCharacterFromSet:tmpInvalidMutableCharSet];
            if(rangeOfInavlidChars.length !=0 || [string isEqualToString:@""])
                return NO;
        }
     
        return YES;
    }
    else // no ''@'' or ''.'' present
        return NO;
}




BOOL NSStringIsValidEmail(NSString *checkString)  
{  
    NString *stricterFilterString = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"; 
    NSString *laxString = @".+@.+\.[A-Za-z]{2}[A-Za-z]*";  
    NSString *emailRegex = stricterFilter ? stricterFilterString : laxString;  
    NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];  
    return [emailTest evaluateWithObject:checkString];  
}