Ndtyjky

I have an iOS App that crashes with certain users. I can't recreate the crash however I do have three identical crash reports. How can I figure out what is causing the crash? (I've looked at https://developer.apple.com/videos/play/wwdc2018/414/ but am still having difficulties.)

Exerpt from the crash report is as follows:

Exception Type:  EXC_BREAKPOINT (SIGTRAP)

Exception Codes: 0x0000000000000001, 0x0000000100fd21ac

Termination Signal: Trace/BPT trap: 5

Termination Reason: Namespace SIGNAL, Code 0x5

Terminating Process: exc handler [5535]

Triggered by Thread:  0



Thread 0 name:

Thread 0 Crashed:

0   libswiftCore.dylib              0x0000000100fd21ac 0x100de0000 + 2040236

1   libswiftCore.dylib              0x0000000100fd21ac 0x100de0000 + 2040236

2   libswiftCore.dylib              0x0000000101027c50 0x100de0000 + 2391120

3   MyApp                           0x000000010081af08 partial apply for closure #3 in DefaultService.processPosts(network:posts:completion:) + 40 (DefaultService.swift:1009)

4   MyApp                           0x000000010087060c thunk for @escaping @callee_guaranteed () -> () + 36 (<compiler-generated>:0)

5   libdispatch.dylib               0x000000021aeb96c8 _dispatch_call_block_and_release + 24 (init.c:1372)

6   libdispatch.dylib               0x000000021aeba484 _dispatch_client_callout + 16 (object.m:511)

The code that seems to be causing the problem DefaultService.swift:1009 in processPosts is as follows:

private func processPosts(network: Network, posts: [Post], completion: @escaping (Result<Void>) -> Void) {

   ...

   dg.notify(queue: .main) {

        self.savePosts(network: network, posts: posts) // This is line 1009.

        completion(.success(()))

    }

}



private func savePosts(network: Network, posts: [Post]) {

    let context = self.container().viewContext



    for post in posts {

        // Don't save if already saved.

        if isPostSaved(context: context, network: network,

                            networkPostID: post.networkPostID!) {

            continue

        }



        let np = NetworkPost(context: context)

        np.id = post.id

        np.network = network.rawValue

        np.networkPostID = post.networkPostID

        np.subtitle = post.subtitle

        np.text = post.text



        for image in post.images {

            let npImage = NetworkPostImage(context: context)

            npImage.data = image

            np.addToImages(npImage)

        }

        if let active = post.active {

            np.active = active

        }

        np.created = post.created

    }



    try! context.save()

}



private func isPostSaved(context: NSManagedObjectContext, network: Network, networkPostID: String) -> Bool {

    let fetchRequest = NSFetchRequest<NetworkPost>(entityName: "NetworkPost")

    let format = "(network == %@) AND (networkPostID == %@)"

    fetchRequest.predicate = NSPredicate(format: format,

                                         network.rawValue,

                                         networkPostID)



    let posts = try! context.fetch(fetchRequest)

    return !posts.isEmpty

}

Is it likely that one of my try! calls in either savePosts or isPostSaved is the culprit causing an EXC_BREAKPOINT?

If so how can I narrow down which one it is? Is there any way of using the first three libswiftCore.dylib calls of the backtrace to figure it out?

If not the try! calls then what else could be causing the EXEC_BREAKPOINT error?

Note that I am using the CoreData API in memory only mode so I expect my try! context.save() and try! context.fetch(fetchRequest) calls to execute unless there is something seriously wrong or I have a programming error. This is why I use try! instead of do { } catch { }.