title: NSMutableSet Not adding object
body: <p>My code isn't adding elements to my sets.</p>
  
  <p>My header file is as follows:</p>
  
  <pre><code>#import &lt;UIKit/UIKit.h&gt;
  
  @interface NHPSearchViewController : UITableViewController
  //For using the local DB
  @property (strong, nonatomic) NSManagedObjectContext *managedObjectContext;
  //texst field where user enters a substance name or a drug name
  @property (weak, nonatomic) IBOutlet UITextField *substanceTextField;
  
  //An array for Drug Names, and another array for NHPs 
  @property (strong, nonatomic) NSMutableSet *drugList;
  @property (strong, nonatomic) NSMutableSet *NHPList;
  //Contains both drugList and NHP list as one array for the data to be shown for the user.
  @property (strong, nonatomic) NSMutableSet *usersList;
  
  @end
  </code></pre>
  
  <p>My .m file:</p>
  
  <pre><code>@interface NHPSearchViewController ()
  - (BOOL) checkAndAddToList: (NSString *) substance;
  @end
  
  @implementation NHPSearchViewController
  
  @synthesize managedObjectContext;
  @synthesize substanceTextField;
  @synthesize drugList, NHPList, usersList;
  
  //"Private" helper methods
  
  -(BOOL) checkAndAddToList:(NSString *)substance{
      //  Set up a predicate for testing if the data exists in the table
      NSPredicate *pred = [NSPredicate predicateWithFormat:@"name == %@", substance];    
  
      //Run the query to see if the substance is in the Substances Table.
      NSMutableArray  *results =[NSMutableArray array];
      results = [CoreDataHelper searchObjectsForEntity:@"Substances" withPredicate:pred andSortKey:nil andSortAscending:NO andContext:self.managedObjectContext];
  
          if ([results count] &gt; 0){
          //Found the substance return YES
              Substances *sub = [results objectAtIndex:0];        
              NSLog(@"Did find a result with name:%@  and class_name as:%@ ",[sub name], [sub class_name]);
  
              //add the name to the appropriate lists.
              if([[sub class_name] isEqualToString:@"NHP"]){
                  NSLog(@"NHP was found adding it to the nhp list");
                  [NHPList addObject:[sub name]];  //THIS is not working
                  NSLog(@"NHP count after adding %i", [NHPList count]);
              }else if ([[sub class_name] isEqualToString:@"Drugs"]){
                  NSLog(@"Drug was found adding it to the drug list");
                  [drugList addObject:[sub name]];  //THIS is also not working
              }
  
              //add the name to our list in the view
              [usersList addObject:[sub name]]; //This is also not working
  
              return YES;
      }else{
        // 
         return YES;
  
      }
   return NO;
  }
  </code></pre>
  
  <p>The log output:</p>
  
  <blockquote>
    <p>[4187:fb03] Testing substanceTextField value: Omega 3-6-9 [4187:fb03]
    Did find a result with name:Omega 3-6-9  and class_name as:NHP 
    [4187:fb03] NHP was found adding it to the nhp list [4187:fb03] NHP
    count after adding 0 [4187:fb03] NHP List:0 DrugList:0 UserList:0</p>
  </blockquote>