判断邮箱是否合法

-(BOOL)validateEmail:(NSString*)email
{
    if((0 != [email rangeOfString:@"@"].length) &&
       (0 != [email rangeOfString:@"."].length))
    {
 
        NSCharacterSet* tmpInvalidCharSet = [[NSCharacterSet alphanumericCharacterSet] invertedSet];//可以判断一个NSString字符串里面是否只含有 a-z 0-9字符
        NSMutableCharacterSet* tmpInvalidMutableCharSet = [[tmpInvalidCharSet mutableCopy] autorelease];//
mutableCopy是深拷贝，即对象拷贝，可以改变对象的内容
        [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:@"@"                                      options: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;}

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