MutableArrayInsertTest.m

        // Initialize Array
        NSMutableArray *dumbArray = [NSMutableArray new];
        
        // Basically addObject
        [dumbArray addObject:@"A"];
        [dumbArray addObject:@"B"];
        [dumbArray addObject:@"C"];
        [dumbArray addObject:@"D"];
      
        // Insert Object at the top array
        [dumbArray insertObject:@"0" atIndex:0];

        // Create Array And IndexSet
        NSArray *dumbArray2 = @[@"-3", @"-2", @"-1"];
        NSIndexSet *dumbIndexSet = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, [dumbArray2 count])];
        
        // Insert Array at the top of array
        [dumbArray insertObjects:dumbArray2 atIndexes:dumbIndexSet];