filterduplicates.m

#import <Foundation/Foundation.h>


@interface Item : NSObject
@property NSInteger itemID;
@property NSInteger typeID;
@property(copy) NSString *itemDescription;
@end

@implementation Item

-(NSString *)description
{
    return [NSString stringWithFormat:@"Item: %li, typeID: %li, description: %@", (long)self.itemID, (long)self.typeID, self.itemDescription];
}
@end




int main(int argc, const char * argv[])
{

    @autoreleasepool {

        
        
        NSArray *data =@[ @{@"itemID": @1, @"typeID": @7, @"description": @"some text 1"},
                          @{@"itemID": @2, @"typeID": @7, @"description": @"some text 2"},
                          @{@"itemID": @3, @"typeID": @5, @"description": @"some text 3"},
                          @{@"itemID": @4, @"typeID": @5, @"description": @"some text 4"},
                          @{@"itemID": @5, @"typeID": @8, @"description": @"some text 5"}];
        
        NSMutableArray *items = [@[ ] mutableCopy];
        
        
        [data enumerateObjectsUsingBlock:^(NSDictionary *obj, NSUInteger idx, BOOL *stop) {
            [items addObject:({
                Item *item = [[Item alloc] init];
                item.itemID = [obj[@"itemID"] integerValue];
                item.typeID = [obj[@"typeID"] integerValue];
                item.itemDescription = obj[@"description"];
                item;
            })];
        }];
        
        NSMutableDictionary *itemsByType = [@{} mutableCopy];
        
        [items enumerateObjectsUsingBlock:^(Item *item, NSUInteger idx, BOOL *stop) {
            id key = @(item.typeID);
            if (![[itemsByType allKeys] containsObject:key]) {
                itemsByType[key] = [@[] mutableCopy];
            }
            [itemsByType[key] addObject:item];
        }];
        
        [itemsByType enumerateKeysAndObjectsUsingBlock:^(id key, NSMutableArray *items, BOOL *stop) {
            
            [items sortUsingComparator:^NSComparisonResult(Item *item1, Item *item2) {
                return item1.itemID < item2.itemID;
            }];
            
        }];
        
        NSMutableArray *resultArray = [@[] mutableCopy];
        
        [[itemsByType allKeys]  enumerateObjectsUsingBlock:^(id key, NSUInteger idx, BOOL *stop) {
            [resultArray addObject:itemsByType[key][0]];
        }];
        
        [resultArray sortUsingComparator:^NSComparisonResult(Item *item1, Item *item2){
            return item1.itemID > item2.itemID;
        }];
        
        NSLog(@"%@", resultArray);
        
    }
    return 0;
}