billibala / ManagedObjectRetainCycle

ManagedObjectRetainCycle

An example of how strong reference cycle happens in Core Data managed objects relationship.

Seed test data

• Open the workspace file from Xcode
• Run the project
• Click Seed Data button to seed some test data into the database.
• Quit the app (to avoid any lingering managed objects from the seeding process)

Transverse unidirectionally

• Run the project again
• From the sample app window, click Transverse a project button
• In Xcode, click the Debug Memory Graph button from debug toolbar
• Try searching for any todo object using the Filter at the bottom left of the window.

Expectation: only 1 todo object remains. No extra ones.

Transverse bi-directionally

• Run the project
• From the sample app window, click Transverse and Invoke Parent
• In Xcode, click the Debug Memory Graph button from debug toolbar
• Try searching for any todo object using the Filter at the bottom left of the window.

Expectation: Lots of todo object persisting in memory.

What's the behavior when creating managed objects?

When creating new mananged objects, the behavior is the same.

Creating a parent object. Then, assign child object to it does not create strong reference cycle. Strong reference cycle occurs when the parent and child objects reference to each other in the same autorelease pool scope (not tested yet).