iPhone NSString comparison having Extended ASCII or Latin 1 Unicode character set

Question

I am having problem with NSString compare. The localizedCaseInsensitiveCompare: or any other compare: method in NSString is returning wrong result to me with extended ascii character set. for example below code, after comparison, noString should be after the enString1.

any idea, how can I solve the problem?

NSString * noString = @"ÅåÆæØøab"; // ASCII values, 197, 229, 198, 230, 216, 248, 97, 98

    NSString * enString1 = @"fbcd";
    NSString * enString2 = @"bbcd";
    NSString * enString3 = @"zbcd";

    NSLog(@"%i", [enString1 localizedCaseInsensitiveCompare:enString2]); // 1
    NSLog(@"%i", [enString1 localizedStandardCompare:noString]); // 1, should be -1
    NSLog(@"%i", [enString1 localizedCaseInsensitiveCompare:noString]); // 1, should be -1

"aa" compareTo "aå" is returning Ascending. Thats right. But,

"aa" compareTo "aæ" is returning Descending, why? same for "aø" too.

Answer 1

The following way can be solution, but it works for comparison with å but not for ø and æ.

NSLog(@"%i", [enString1 compare:noString options:NSCaseInsensitiveSearch 
                              range:NSMakeRange(0, [enString1 length])  
                             locale:[[NSLocale alloc] initWithLocaleIdentifier:@"no"] ]);

Answer 2

Find here More on string operations

If anybody stubmle upon this question, this is how I made a solution. It seems there is still some problem with non-english characters in NSString comparison. Specially for Å, Ø and Æ etc. The sorting order seems AÅ...ÆØ even with localized compare. THough ASCII code is different. So I wrote my own comparison method,

- (NSComparisonResult) caseInsensitiveStringCompare:(NSString *)string1 
                                      anotherString:(NSString *)string2 
{
    NSString * ciString1 = [string1 lowercaseString];
    NSString * ciString2 = [string2 lowercaseString];
    return [self stringCompare:ciString1 anotherString:ciString2];
}

- (NSComparisonResult) stringCompare:(NSString *)string1 
                          anotherString:(NSString *)string2
{
    int len1 = [string1 length];
    int len2 = [string2 length];

    if (len1 < len2) {
        int i = 0;

        while ( i < len1 && [string1 characterAtIndex:i] == [string2 characterAtIndex:i]  ) 
        {
            i++;
        }
        if (i == len1) {
            return NSOrderedAscending;
        } else if ([string1 characterAtIndex:i] < [string2 characterAtIndex:i]) {
            return NSOrderedAscending;
        } else {
            return NSOrderedDescending;
        }

    } else { // str1 >= str2 len
        int i = 0;

        while ( i<len2 && [string1 characterAtIndex:i] == [string2 characterAtIndex:i]) 
        {
            i++;
        }
        if (i == len2 && i == len1) {
            return NSOrderedSame;
        } else if (i == len2){
            return NSOrderedDescending;
        } else if ([string1 characterAtIndex:i] < [string2 characterAtIndex:i]) {
            return NSOrderedAscending;
        } else {
            return NSOrderedDescending;
        }
    }

    return NSOrderedSame;
}