CODEWITHSUNDEEP
iosuitableviewmemory-management
MrTJ
MrTJ

Reputation: 13202

viewDidUnload sent to deallocated instance after memory warning

I faced a very interesting situation and do not know how to resolve it. I'll outline first the architecture of my program. I have a UITableViewController derived class that also implements a my delegate protocol. The cells in this table view are custom cells, and each of them have a strong (assign) type property to the delegate (the table view controller). The delegate handle some UI action.

To reproduce the crash, I load the table view, and then navigate away from it. Normally here the table view would be dealloced but in my case the cells still hold the strong reference to it, so it remains in the memory. The problem is that I get a crash when a memory warning arrives to the device after this. I deducted that the following happens:

How can I resolve this situation?

PS: obviously I don't use ARC

Upvotes: 1

Views: 277

Answers (1)

Alexander
Alexander

Reputation: 8147

When you're setting a delegate, you should assign it, not retain it (and so the deallocation of the cells should not send a release message to the table view controller).

Delegating objects do not (and should not) retain their delegates. However, clients of delegating objects (applications, usually) are responsible for ensuring that their delegates are around to receive delegation messages. To do this, they may have to retain the delegate in memory-managed code. This precaution applies equally to data sources, notification observers, and targets of action messages. Note that in a garbage-collection environment, the reference to the delegate is strong because the retain-cycle problem does not apply.

From Concepts in Objective-C Programming

Upvotes: 3

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