PHAssetCollection fetchAssetCollectionsWithType crashes

Question

The following method was put on the default global queue in order to get a few photos from device. if system version is greater than iOS 8, Photos framework is used, otherwise ALAssetLibrary.

dispatch_semaphore_t sema = dispatch_semaphore_create(0);

dispatch_async(dispatch_get_global_queue(0, 0), ^{
   [self getPhotos:^(NSArray *photos) {
       dispatch_semaphore_signal(sema);
    }];
}

dispatch_time_t timeout = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(10 * NSEC_PER_SEC));

dispatch_semaphore_wait(sema, timeout);


- (void)getPhotos:(MyCallBack)callback {

  Class PHPhotoLibrary_class = NSClassFromString(@"PHPhotoLibrary");

   if (PHPhotoLibrary_class) {

    PHAuthorizationStatus status = [PHPhotoLibrary authorizationStatus];


    if (status != PHAuthorizationStatusAuthorized)
    {
        return;
    }

    PHFetchResult *smartAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil];

  }       
}

The app crashes, on 64bit device, such as iPhone 5S and newer model, the stack trace is like this.

Exception Type:  SIGTRAP
Exception Codes: TRAP_BRKPT at 0x190c41b60
Crashed Thread:  25

Thread 25 Crashed:
0   PhotoLibraryServices            0x0000000190c41b60 +[PLModelMigrator _validateCurrentModelVersionFailedWithNoVersionFromServer] :444 (in PhotoLibraryServices)
1   PhotoLibraryServices            0x0000000190c41ef8 +[PLModelMigrator _validateCurrentModelVersionAttempt:] :316 (in PhotoLibraryServices)
2   PhotoLibraryServices            0x0000000190c41ef8 +[PLModelMigrator _validateCurrentModelVersionAttempt:] :316 (in PhotoLibraryServices)
3   PhotoLibraryServices            0x0000000190c41ef8 +[PLModelMigrator _validateCurrentModelVersionAttempt:] :316 (in PhotoLibraryServices)
4   PhotoLibraryServices            0x0000000190c41ef8 +[PLModelMigrator _validateCurrentModelVersionAttempt:] :316 (in PhotoLibraryServices)
5   PhotoLibraryServices            0x0000000190c41ef8 +[PLModelMigrator _validateCurrentModelVersionAttempt:] :316 (in PhotoLibraryServices)
6   PhotoLibraryServices            0x0000000190c41ef8 +[PLModelMigrator _validateCurrentModelVersionAttempt:] :316 (in PhotoLibraryServices)
7   PhotoLibraryServices            0x0000000190c41ef8 +[PLModelMigrator _validateCurrentModelVersionAttempt:] :316 (in PhotoLibraryServices)
8   PhotoLibraryServices            0x0000000190c41ef8 +[PLModelMigrator _validateCurrentModelVersionAttempt:] :316 (in PhotoLibraryServices)
9   PhotoLibraryServices            0x0000000190c41ef8 +[PLModelMigrator _validateCurrentModelVersionAttempt:] :316 (in PhotoLibraryServices)
10  PhotoLibraryServices            0x0000000190c41ef8 +[PLModelMigrator _validateCurrentModelVersionAttempt:] :316 (in PhotoLibraryServices)
11  PhotoLibraryServices            0x0000000190c43688 +[PLModelMigrator createDatabase] :508 (in PhotoLibraryServices)
12  PhotoLibraryServices            0x0000000190b7c1cc -[PLPhotoLibrary loadDatabase:] :808 (in PhotoLibraryServices)
13  PhotoLibraryServices            0x0000000190b71f70 -[PLPhotoLibrary initWithTransientContext:name:] :560 (in PhotoLibraryServices)
14  Photos                          0x0000000191722418 ___45-[PHPhotoLibrary backgroundQueuePhotoLibrary]_block_invoke :60 (in Photos)
15  libdispatch.dylib               0x0000000184bb21bc __dispatch_client_callout :16 (in libdispatch.dylib)
16  libdispatch.dylib               0x0000000184bb2fb0 _dispatch_once_f :56 (in libdispatch.dylib)
17  Photos                          0x00000001917223d4 -[PHPhotoLibrary backgroundQueuePhotoLibrary] :156 (in Photos)
18  Photos                          0x0000000191722604 -[PHPhotoLibrary photoLibraryForCurrentQueueQoS] :80 (in Photos)
19  Photos                          0x0000000191722578 -[PHPhotoLibrary managedObjectContextForCurrentQueueQoS] :24 (in Photos)
20  Photos                          0x00000001917611bc -[PHQuery _createFetchRequestIncludingBasePredicate:] :140 (in Photos)
21  Photos                          0x0000000191761c5c -[PHQuery fetchRequest] :52 (in Photos)
22  Photos                          0x0000000191783988 -[PHFetchResult initWithQuery:oids:registerIfNeeded:usingManagedObjectContext:] :376 (in Photos)
23  Photos                          0x0000000191783c2c -[PHFetchResult initWithQuery:] :100 (in Photos)
24  Photos                          0x0000000191763b5c -[PHQuery executeQuery] :52 (in Photos)
25  Photos                          0x00000001916c2998 ___67+[PHAssetCollection fetchAssetCollectionsWithType:subtype:options:]_block_invoke :72 (in Photos)
26  Photos                          0x000000019175fe48 +[PHObject authorizationAwareFetchResultWithOptions:fetchBlock:] :88 (in Photos)
27  Photos                          0x00000001916c2944 +[PHAssetCollection fetchAssetCollectionsWithType:subtype:options:] :84 (in Photos)

Usually on 32bit devices, such as iPhone5, iPhone4S, crash report is like this:

Exception Type:  SIGABRT
Exception Codes: #0 at 0x1b448ad4
Crashed Thread:  1
Application Specific Information:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException'  reason: 'CoreData: Cannot load NSManagedObjectModel.  nil is an illegal URL parameter'
Last Exception Backtrace:
0   CoreFoundation                  0x1bca0df7 ___exceptionPreprocess :131 (in CoreFoundation)
1   libobjc.A.dylib                 0x1af03077 _objc_exception_throw :39 (in libobjc.A.dylib)
2   CoreData                        0x1dc190c5 +[NSManagedObjectContext initialize] :1 (in CoreData)
3   PhotoLibraryServices            0x256a45d5 ___44+[PLManagedObjectContext managedObjectModel]_block_invoke :89 (in PhotoLibraryServices)
4   AssetsLibraryServices           0x24fc527d ___pl_dispatch_once_block_invoke :19 (in AssetsLibraryServices)
5   libdispatch.dylib               0x1b346083 __dispatch_client_callout :23 (in libdispatch.dylib)
6   libdispatch.dylib               0x1b346c65 _dispatch_once_f :43 (in libdispatch.dylib)
7   AssetsLibraryServices           0x24fc5267 _pl_dispatch_once :77 (in AssetsLibraryServices)
8   PhotoLibraryServices            0x256a456d +[PLManagedObjectContext managedObjectModel] :73 (in PhotoLibraryServices)
9   Photos                          0x26139475 +[PHQuery _relationshipForFetchType:predicate:] :257 (in Photos)
10  Photos                          0x2613a4cd -[PHQuery collectionFetchType] :85 (in Photos)
11  Photos                          0x261392b1 -[PHQuery copyWithZone:] :303 (in Photos)
12  Photos                          0x26158239 -[PHFetchResult initWithQuery:oids:registerIfNeeded:usingManagedObjectContext:] :125 (in Photos)
13  Photos                          0x26158567 -[PHFetchResult initWithQuery:] :81 (in Photos)
14  Photos                          0x2613c0cb -[PHQuery executeQuery] :53 (in Photos)
15  Photos                          0x260aaf4f ___67+[PHAssetCollection fetchAssetCollectionsWithType:subtype:options:]_block_invoke :73 (in Photos)
16  Photos                          0x2613898d +[PHObject authorizationAwareFetchResultWithOptions:fetchBlock:] :63 (in Photos)
17  Photos                          0x260aaf03 +[PHAssetCollection fetchAssetCollectionsWithType:subtype:options:] :97 (in Photos)

It seems like a coredata error, I also don't understand why AssetsLibraryServices and PhotoLibraryServices both exist in the last crash report. I tried many ways but can't reproduce the crash, Any help is appreciated.

Answer 1

A couple things are missing here, mainly context for your call to getPhotos and I notice you never do anything with smartAlbums or call back. Maybe you just didn't include it because you didn't think it was relevant.

Anyway, I created a new project (including core data) and here is literally everything I did. Working with no crash:

1) Added NSPhotoLibraryUsageDescription to plist

2) Added the following to AppDelegate.h:

#import <Photos/Photos.h>

typedef void (^MyCallBack)(NSArray *photos);

3) Replace the default implementation of didFinishLaunchingWithOptions in AppDelegate.m with this:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    dispatch_semaphore_t sema = dispatch_semaphore_create(0);

    [PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {

        if (status == PHAuthorizationStatusAuthorized) {
            dispatch_async(dispatch_get_global_queue(0, 0), ^{
                [self getPhotos:^(NSArray *photos) {
                    dispatch_semaphore_signal(sema);
                }];
            });
        }
    }];

    dispatch_time_t timeout = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(10 * NSEC_PER_SEC));

    dispatch_semaphore_wait(sema, timeout);

    return YES;
}

- (void)getPhotos:(MyCallBack)callback {

    Class PHPhotoLibrary_class = NSClassFromString(@"PHPhotoLibrary");

    if (PHPhotoLibrary_class) {

        PHFetchResult *smartAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil];

        NSMutableArray *photos = [[NSMutableArray alloc] init];

        int i = 0;
        for (PHAssetCollection *assetCollection in smartAlbums)
        {
            i++;

            PHFetchResult *smartAlbum = [PHAsset fetchAssetsInAssetCollection:assetCollection options:nil];

            int j = 0;
            for (PHAsset *asset in smartAlbum)
            {
                j++;

                [[PHImageManager defaultManager]
                 requestImageDataForAsset:asset
                 options:nil
                 resultHandler:^void(NSData * _Nullable imageData, NSString * _Nullable dataUTI, UIImageOrientation orientation, NSDictionary * _Nullable info) {

                     [photos addObject:[UIImage imageWithData:imageData]];
                     if (i == [smartAlbums count] && j == [smartAlbum count]) {
                         callback([NSArray arrayWithArray:photos]);
                     }
                 }];

                if (i == [smartAlbums count] && j == [smartAlbum count]) {
                    return;
                }
            }
        }
    }
}