NSException Error - Swift 4

Question

stack overflow community. Please don't mark this question as a duplicate as I have seen all the other posts regarding this and have pretty much gone through most of the famous solutions.

Currently, I have some code that allows a user to send messages to a group and also change the group thumbnail and title. However, upon the user doing any of this, my code crashes. I am storing my data in firebase (the data is being successfully uploaded). The problem began when I upgraded from swift 3 to swift 4. Also, this is the specific error I am getting:

libc++abi.dylib: terminating with uncaught exception of type NSException

Here are some solutions/methods I have tried to solve my problem:

1. I have outruled that this is an outlet problem as the view controller is programmatically created.
2. I tried adding an exception breakpoint but it didn't show me any specific lines of code for where the crash occurred.
3. I have also tried cleaning, re-building, and closing Xcode however that doesn't work as well.
4. I don't think its a problem with uploading data to firebase as I am able to in other parts of my app.
5. I have also tried scrolling through the threads to get a deeper understanding of where the crash occurs, however that has not been of much help.

Here is a picture of my console output:

Here is the code I use to update the collection view:

func observeConversationMessagesWithConversationId(conversationId: String) {
    Database.database().reference().child("conversation-messages").child(conversationId).observe(.childAdded, with: { (snapshot) in
        if let messages = ConversationMessages(snapshot: snapshot) {

            self.conversationMessages.append(messages)

            DispatchQueue.main.async(execute: {
                self.collectionView?.reloadData()

                let indexPath = NSIndexPath(item: self.conversationMessages.count - 1, section: 0)
                self.collectionView?.scrollToItem(at: indexPath as IndexPath, at: .bottom, animated: true)
            })
        }
    }, withCancel: nil)
}

Here is my podfile

Any help would be appreciated. Please note that I would have added some code but I have no clue where the error occurs.

Answer 1

Since you don't know where the error occurs, it might be a good idea to place a few breakpoints in your code so you can pinpoint the crash. Then it will be a lot easier to fix the error when you know the exact line where it happens.

I had the same crash and it was related to UIVisualEffectView, and specifically with adding a subview to it instead of adding it to its .contentView.

If that is your case too, you can find more details here.

Good luck bug hunting.