Question

I have a super class ‘Node’ and several sub classes e.g. ‘SubNode1’, ‘SubNode2’ etc.

I need to have a property which all the sub classes need called ‘parentNode’. It gets set when init is called on ‘SubNode1’ and the object is passed through of type ‘Node’. The reason I used a sub class is because these objects are comforming to a protocol and I cannot use the sub class each time – I need to pass ‘Node’ around.

What I don’t know is how to structure my objects. Where should the release be and where should the property be and should it be retain as I constantly get exe_bad_access errors because of this.

This is how I have structured it currently:

Node.h

 @property (nonatomic, retain) Node *parentNode;

Node.m

- (void)dealloc {
    [parentNode release];
    [super dealloc];
}

SubNode1.h

@interface SubNode1 : Node
{
    // No reference to parentNode property
}

SubNode1.m

- (id)initWithParentNode:(SubNode1 *)theParentNode {
    self = [super init];
    if (self) 
    {
        super.parentNode = theParentNode;
    }

    return self;
}

- (void)dealloc {
    [super dealloc];
}

Answer 1

You’re already designing it the correct way. The error is probably that:

super.parentNode = theParentNode;

should be:

self.parentNode = theParentNode;