Objective C Array and Object Release

Question

I have a newbie question regarding when to release the elements of a NSArray. See following pseudo code:

NSMutalbeArray *2DArray = [[NSMutableArray alloc] initWithCapacity:10];
for (int i=0;i<10;i++) {
  NSMutableArray *array = [[NSMutableArray alloc] initWithCapacity:5];
  for (int j=0;j<5;j++) {
    MyObject *obj = [[MyObject alloc] init];
    [array addObject:obj];
    [obj release];
  }

  [2DArray addObject:array];
  [array release];
}
// use 2DArray to do something

[2DArray release]

My question here is, when I release 2DArray, do I need to explicitly release each of its element (array) first? Also, before I release the "array" object, do I need to release each of its element (MyObject) first?

I am new to Objective C. Please help. thanks.

Answer 1

No, you don't need to tell each object to be released. When you send a release method to an NSArray, it automatically sends a release method to each item inside first.

So in your case, you send [2DArray release]. This automatically sends [array release] to every other array, which sends [obj release] to each object inside each array.