iOS 9.0 - NSMutableDictionary causing EXC_BAD_ACCESS

Question

My application includes a singleton class represents general data. The latter contains the following atomic property :

// .h file
@property (atomic, strong) NSMutableDictionary *dataDictionary;

// .m file
@synthesize dataDictionary;

The dictionary is being used simultaneously from different threads (both setter and getter), and worked as normal without any crashes on iOS 6.0 - 8.4. Recently I have run the application on iOS 9.0 simulator and it crashed (EXC_BAD_ACCESS) in arbitrary code calling the dictionary setObject:forKey: method.

Does anyone knows what have changed in iOS 9.0 that can cause those crashes ?
Any clue how to solve this issue ?

Check you dictionary it may have value null for key. – Dhaivat Vyas Sep 30 '15 at 06:57 — Dhaivat Vyas, Sep 30 '15 at 06:57
You means value is null OR key is null ? – Tsahi Deri Sep 30 '15 at 07:03 — Tsahi Deri, Sep 30 '15 at 07:03
@iOS_DK, value and key aren't null (for sure). – Tsahi Deri Sep 30 '15 at 07:29 — Tsahi Deri, Sep 30 '15 at 07:29

score 2 · Answer 1 · answered Sep 30 '15 at 07:09

atomic on a property doesn't mean what you think it does. atomic means that the property value itself (i.e. the pointer) is protected from parallel access, but it doesn't protect the contents of the dictionary at all.

If your code worked on previous versions of iOS, then it was completely by fluke. Your code will crash randomly if you are allowing multiple threads to access a single NSMutableDictionary in this way.

You need to add a locking discipline of some sort between these multiple threads.

score 0 · Answer 2 · answered Sep 30 '15 at 07:37

0

I think you should use nonatomic instead of atomic

answered Sep 30 '15 at 07:37

Dipen

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The same behavior occurs with nonatomic. – Tsahi Deri Sep 30 '15 at 07:50

iOS 9.0 - NSMutableDictionary causing EXC_BAD_ACCESS

2 Answers2