[Objective-C] Basic Concepts
Property
Use weak property to avoid strong reference cycle
- Typical senario: delegate
+---------------------------------------------------------------------+
| NSTableView: Delegate Object: |
| strong |
| ---------> |
| @property id delegate; @property NSTableView *tableview; |
| <--------- |
| strong |
+---------------------------------------------------------------------+
- Solution: declare ‘delegate’ as weak property
+----------------------------------------------------------------------------+
| NSTableView: Delegate Object: |
| weak |
| ---------> |
| @property (weak) id delegate; @property NSTableView *tableview; |
| <--------- |
| strong |
+----------------------------------------------------------------------------+
Use object cache to keep weak object alive
- In order to keep a weak object alive, assign it to a strong object (object cache).
- Then use the object cache to access the content that the weak object points to.
- Assign nil to the object cache when things are done.
Use copy property
- If an object wishes to keep its own copy of its property objects, declare these objects with copy property