Rebuild an NSArray by grouping objects that have matching id numbers?

Question

I have an NSArray and each object in the array has a groupId and a name. Each object is unique but there are many with the same groupId. Is there a way i can tear the arra

Answer 1

The below code will Rebuild an NSArray by grouping objects w.r.t any matching keys in each dictionary in that array

//only to a take unique keys. (key order should be maintained)
NSMutableArray *aMutableArray = [[NSMutableArray alloc]init];

NSMutableDictionary *dictFromArray = [NSMutableDictionary dictionary];

for (NSDictionary *eachDict in arrOriginal) {
  //Collecting all unique key in order of initial array
  NSString *eachKey = [eachDict objectForKey:@"roomType"];
  if (![aMutableArray containsObject:eachKey]) {
   [aMutableArray addObject:eachKey];
  }

  NSMutableArray *tmp = [grouped objectForKey:key];
  tmp  = [dictFromArray objectForKey:eachKey];

 if (!tmp) {
    tmp = [NSMutableArray array];
    [dictFromArray setObject:tmp forKey:eachKey];
 }
[tmp addObject:eachDict];

}

//NSLog(@"dictFromArray %@",dictFromArray);
//NSLog(@"Unique Keys :: %@",aMutableArray);

//Converting from dictionary to array again...

self.finalArray = [[NSMutableArray alloc]init];
for (NSString *uniqueKey in aMutableArray) {
   NSDictionary *aUniqueKeyDict = @{@"groupKey":uniqueKey,@"featureValues":[dictFromArray objectForKey:uniqueKey]};
   [self.finalArray addObject:aUniqueKeyDict];
}

Hope it may help..