Strong/retain for next, weak/assign for previous.
On Nov 14, 2012, at 7:59 PM, William Squires wrote:
> Let's say I have:
>
> @interface Thing : NSObject
>
> @property (nonatomic, ???) Thing *nextThing;
> @property (nonatomic, ???) Thing *prevThing;
>
> @end
>
> and somewhere I keep a reference to the 'head' of this doubly-linked list.
> What should ??? be, "retain", or "assign" in order to work properly? If I was
> using ARC instead, would they be "strong" or "weak"? Assuming the list
> doesn't contain circular references (i.e. a<->b<->c<->a) will releasing my
> 'head' reference properly clean up if I have:
>
> "doublist.h"
> @class Thing;
>
> @interface DoublyLinkedListClass
>
> @property (nonatomic, retain) Thing *head;
>
> @end
>
> "doublist.m"
> @implementation DoublyLinkedListClass
>
> @synthesize head = _head;
>
> …
>
> -(void)dealloc
> {
> self.head = nil; // Is this begging for a problem?
no in ARC (but it's unnecessary), yes in MRC; you should [head release];
instead, or you'll leak memory.
-Dan
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