Binary Tree in Objective-C

Question

I am learning algorithms and data structures and to train I am trying to design and implement a binary tree using objective-c.

So far I have the following Classes:

Answer 1

(Node **)node is a pointer to an object pointer so node.something is invalid because you are a reference to far away from the object.

But (*node).something will work.

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Addition for comments :
When you originally call this method : -(void)insertNodeByRef:(Node **)node forRoot:(Node **)root how do you call it?
From the error you've post in your comment it look to me that you are doing :
Node *n = [[Node alloc] init];
[aNode insertNodeByRef:n forRoot:aRoot];

when your method signature state that you need to call it like this :
[aNode insertNodeByRef:&n forRoot:&aRoot];
To pass the address of the pointer to the object.

I'm saying this because your error is now stating that your are sending Node * instead of Node ** which are 2 different thing. (( Incompatible pointer types sending 'Node *' to parameter of type 'Node **' ) I've remove the __autoreleasing between the 2 *, it was obscuring the error message.)
So in other word you are passing a pointer to an object when your method is asking for a pointer TO A pointer to an object.