iOS CRASH issue - SIGSEGV

Question

My application crashes while using NSSortDescriptor on a NSMutableSet .

Here is the code

NSArray *sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:EIKNewsHeadlineAttributeHeadlineId ascending:YES]];

NSArray *orderedHeadlines = [weakSelf.storedHeadlines sortedArrayUsingDescriptors:sortDescriptors];

Here storedHeadlines is the NSMutableSet and my sort descriptor key is EIKNewsHeadlineAttributeHeadlineId which is a NSString @"headlineId” .

My mutable set contains objects of a certain class type and that class has a property called headlineId on which I am trying to sort the mutable set.

I am performing this sorting inside a performBlock on a private Queue. I checked my weakSelf and the NSMutableSet . Both are non nil.

What is causing the issue?

Answer 1

From the crash log it looks like some of the elements in your array are not NSString . The line that says this is objc_msgSend() selector name: length

This means the objects in the array do not respond to the length selector.

I believe the problem is in the JSON to mutable set parsing. If you would print the contents of the set, right before you sort it, it might give you an idea what objects in the array are the wrong ones.

Could you post the code that parses the JSON?

If it is not possible, you could filter the set before sorting, eliminating all elements that are not of type NSString