You do not need to specify `readwrite` (it's implicit) but you need to specify `strong`.

Basically, what will happen when you assign objects here...
1. They won't be retained. (because it's not strong)
2. You'll hold on to the pointer. (because it's not weak)
3. You'll try to access one of these objects (because you want to store them for a useful reason)
4. You'll get an EXC_BAD_ACCESS as it attempts to access memory that is now allocated for another object.