Allows external storage and iOS 12

Wow, we had issues with people reporting nil images, but it turns out now that when restarting the app, the images to external data are indeed empty.....!!!

Major bug. What can we do to get these images back??

http://ileyf.cn.openradar.appspot.com/44884416

Also reproducible in iOS 12.1 beta

https://stackoverflow.com/questions/52586564/ios-12-specific-problem-core-data-external-storage-binary-data-corruption

Sad news is that I have no solution on how to get the images back. I have now ended up on rolling out an update which does two things:
1. Does not save or read images from the Core Data database anymore, instead saves the images to file system and reads them from there. My record has an UUID so I will just have an image with that UUID as its filename to reference, pretty simple. And now I am in full control of saving and deleting those files.

2. At first launch of the next version, all existing images (if there are still any 🙂) are copied to this directory.

I realized that the bug for me was also worse because I did an extra context save when saving the image, that extra save caused the image to disappear always. Like discussed in that SO post and bug report, this nilling seems to happen with every other save call.

I have been testing this as well and added some crude debugging. I can see that after several saves, my external data folder keeps increasing. But my data model has nil fields for these binary objects. My app uses app groups to share data, so that is the reason for the "forSecurityApplicationGroupIdentifier". But I'm not sure where the relationship exists between the filename and the core data object.

So while I can fix this to store the data myself, seems like some care should be taken with this old data.

let externalStorage = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: "group.countdownwithme.coredata")?.appendingPathComponent(".CountdownModel_SUPPORT/_EXTERNAL_DATA") as! URL

do {

let filePaths = try FileManager.default.contentsOfDirectory(at: externalStorage, includingPropertiesForKeys: nil

, options: [])

print(filePaths.count)

for filePath in filePaths {

print(filePath)

do {

let data = try Data(contentsOf: filePath)

print(data.count)

} catch {

print(error)

}

}

} catch let error as NSError {

print("Could not view temp folder: \(error.debugDescription)")

}

70

file:///private/var/mobile/Containers/Shared/AppGroup/5CBB96AB-4A20-4A30-A2F5-3126469D9769/.CountdownModel_SUPPORT/_EXTERNAL_DATA/0082C640-C81C-4411-8C66-67B836816FD2

18508308

file:///private/var/mobile/Containers/Shared/AppGroup/5CBB96AB-4A20-4A30-A2F5-3126469D9769/.CountdownModel_SUPPORT/_EXTERNAL_DATA/01C4A863-CA53-4C47-847A-001175E5403D

5165152

file:///private/var/mobile/Containers/Shared/AppGroup/5CBB96AB-4A20-4A30-A2F5-3126469D9769/.CountdownModel_SUPPORT/_EXTERNAL_DATA/05593A04-B958-4EAF-8C3A-03375C5C4FD7

13619329

file:///private/var/mobile/Containers/Shared/AppGroup/5CBB96AB-4A20-4A30-A2F5-3126469D9769/.CountdownModel_SUPPORT/_EXTERNAL_DATA/08EFF8D8-842E-43F4-9113-7BD41B494C02

1771198

FWIW, I created a verion of the sample app that exposes the issue reported in the radar. It seems to be resolved with iOS 12.1 beta 3 released earlier today. There are no notes to confirm this. I was wondering if anyone else has tried and can confirm this?

Glad i found this thread, thought i was going mad.

Same issue for our app, bit of a major disaster, eventually had to switch off external storage as quick fix.

Will test iOS12.1 beta 3 later, but too many unrecoverable hours lost debuggin this problem, thinking it was in the code.

I tried to fix it by creating a new model version where "Allows external storage" was unchecked but i have got an error:

Thread 1: Fatal error: 'try!' expression unexpectedly raised an error: Error Domain=NSCocoaErrorDomain Code=134140 "Persistent store migration failed, missing mapping model."

FYI, this issue appears to be resolved in iOS 12.1 (verified in beta 4 on iPad).

I can confirm that it is most certainly NOT fixed in iOS 12.1.1

Not from where I'm standing with iOS 12.1.1

The problem is still well & truly alive & kicking!