[myMutableArray insertObject:myObject atIndex:42];
To add an object to the front of the array, use 0 as the index:
[myMutableArray insertObject:myObject atIndex:0];
[myMutableArray insertObject:myObject atIndex:42];
To add an object to the front of the array, use 0 as the index:
[myMutableArray insertObject:myObject atIndex:0];