Creating and array of index letters

The following method allows you to supply an array of dictionaries and obtain a sorted index array of any key for use in an indexed tableView;

// Takes the array in question and creates an index for use in the tableview
- (NSArray *)makeSectionsIndex:(NSArray *)arrayOfDictionaries {
   
// Creates a mutable set to read each letter only once   
    NSMutableSet *sectionsMutableSet = [NSMutableSet setWithCapacity:26];
   
// Reads each item's country & loads it's first letter into sections set
    for (int i=0; i<=[arrayOfDictionaries count]-1; i++) {
        NSDictionary *aDictionary = [arrayOfDictionaries objectAtIndex:i];
        NSString *aCountry = [aDictionary objectForKey:@"Country"];
        NSString *aLetter = [aCountry substringToIndex:1U];         //uses first letter of string
        [sectionsMutableSet addObject:aLetter];
    }
   
// Copies the mutable set into a set & then make a mutable array of the set
    NSSet *sectionsSet = [NSSet setWithSet:sectionsMutableSet];
    NSMutableArray *sectionsMutableArray = [[sectionsSet allObjects] mutableCopy];
   
//Now let's sort the array and make it inmutable
    NSMutableArray *sortedMutableArray = [[NSMutableArray alloc] init];
    sortedMutableArray = [sectionsMutableArray        sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
    NSArray *sortedIndexArray = [NSArray arrayWithArray:sortedMutableArray];

//    NSLog(@"%@", sortedIndexArray);
    return sortedIndexArray;                                                  
}

posted from MyMapView, masterViewController by CPL