NSSortDescriptor

gistfile1.m

//How to sort the following list?

//Array with NSStrings:

[NSArray arrayWithObjects:@"0.0 Title", @"1.1 Title", @"1.10 Title", @"1.11 Title", @"1.12 Title", @"1.2 Title", @"10.1 Title",@"10.11 Title",@"10.2 Title",@"2.1 Title", nil];

Solution:

NSSortDescriptor *sortDescriptor;
    
    sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"title" ascending:YES comparator:^NSComparisonResult(id obj1, id obj2) {
            NSArray *obj1Array = [obj1 componentsSeparatedByString:@"."];
            int obj1Chapter = [[obj1Array objectAtIndex:0] intValue];
            int obj1SubChapter = [[obj1Array objectAtIndex:1] intValue];
            
            NSArray *obj2Array = [obj2 componentsSeparatedByString:@"."];
            int obj2Chapter = [[obj2Array objectAtIndex:0] intValue];
            int obj2SubChapter = [[obj2Array objectAtIndex:1] intValue];
            
            //chapter 1 = bigger
            if (obj1Chapter > obj2Chapter) {
                return (NSComparisonResult)NSOrderedDescending;
            }
            //chapter 1 == chapter 2
            if (obj1Chapter == obj2Chapter) {
                if(obj1SubChapter > obj2SubChapter) return (NSComparisonResult)NSOrderedDescending;
                if(obj1SubChapter < obj2SubChapter) return (NSComparisonResult)NSOrderedAscending;
                return (NSComparisonResult)NSOrderedSame;
            }
        
            //chapter 1 = smaller
            if (obj1Chapter < obj2Chapter) {
                return (NSComparisonResult)NSOrderedAscending;
            }
            
            return (NSComparisonResult)NSOrderedSame;
    }];