ALAssetLibrary Notification and EnumerationAssetsUsingBlock

I am creating an iOS application that allows the user to take a picture and save it in a user album, which fills the UICollectionView in the application with photos from the album. I found many examples on the Internet on how to do this, but I could not get past the stubborn problem with the very last picture that did not appear on the album. I ended up using notifications and a sequential send queue, but I think it can be improved.

This is how I save the photos and then re-populate the UICollectionView:

I built a method to call when I need to list a photo album (viewDidLoad and once when I received ALAssetsLibraryChangedNotification).

-(void)setupCollectionView {
    _assets = [@[] mutableCopy];
    __block NSMutableArray *tmpAssets = [@[] mutableCopy];

    // This grabs a static instance of the ALAssetsLibrary
    ALAssetsLibrary *assetsLibrary = [ProfileViewController defaultAssetsLibrary];    

    // Enumerate through all of the ALAssets (photos) in the user’s Asset Groups (Folders)
    [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
        if ([[group valueForProperty:ALAssetsGroupPropertyName] isEqualToString:albumName]) {
            // Make sure we have the group... (this may be redundant) 
            if (group == nil){
                return;
            }

            // I read in some SO posts that setting the filter might help, but I don't think it does
            NSLog(@"Refresh pictures - %d",[group numberOfAssets]);
            [group setAssetsFilter:[ALAssetsFilter allPhotos]];//this will cause group to reload
            if (group!=nil) {
                [group enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {
                    if(result){
                        [tmpAssets addObject:result];
                    }else{
                        *stop = YES;
                    }
                }];
            }

            self.assets = tmpAssets;

            // Reload the UICollectionView
            dispatch_async(dispatch_get_main_queue(), ^{
                [self.collectionView reloadData];
                [self.collectionView.collectionViewLayout invalidateLayout];
            });
        }
    } failureBlock:^(NSError *error) {
        NSLog(@"Error loading images %@", error);
    }];
}

, , , , , , , . ( "" ), , .

, ALAssets, ALAssetsLibraryChangedNotification, . , :

- (void) handleAssetChangedNotifiation:(NSNotification *)notification {
    NSDictionary *userInfo = notification.userInfo;
    NSSet *updateAssets = userInfo[ALAssetLibraryUpdatedAssetsKey];
    if (updateAssets.count>0) {        
        dispatch_sync(photoLoadQueue, ^{
            [self setupCollectionView];
        });
    }
}

. , - ALAssetLibraryUpdatedAssetsKey, , , , . , , :

Received notification: NSConcreteNotification 0x15ed4af0 {name = ALAssetsLibraryChangedNotification; object = <ALAssetsLibrary: 0x15db9e80>; userInfo = {
ALAssetLibraryUpdatedAssetGroupsKey = "{(\n    assets-library://group/?id=43E80EF8-EA91-4C71-AFD2-EBDCB53A1D53\n)}";
ALAssetLibraryUpdatedAssetsKey = "{(\n    assets-library://asset/asset.JPG?id=63E43AF3-3729-43E9-806C-BE463116FDA2&ext=JPG,\n    assets-library://asset/asset.JPG?id=FA2ED24E-DF0F-49A3-85B8-9C181E4077A4&ext=JPG,\n    assets-library://asset/asset.JPG?id=A0B66E2E-6EA1-462C-AD93-DB3087BA65D8&ext=JPG\n)}";}}

Received notification: NSConcreteNotification 0x15d538c0 {name = ALAssetsLibraryChangedNotification; object = <ALAssetsLibrary: 0x15db9e80>; userInfo = {
ALAssetLibraryUpdatedAssetsKey = "{(\n    assets-library://asset/asset.JPG?id=FBDD2086-EC76-473F-A23E-4F4200C0A6DF&ext=JPG\n)}";}}

Received notification: NSConcreteNotification 0x15dc9230 {name = ALAssetsLibraryChangedNotification; object = <ALAssetsLibrary: 0x15db9e80>; userInfo = {}}

Received notification: NSConcreteNotification 0x15df5b40 {name = ALAssetsLibraryChangedNotification; object = <ALAssetsLibrary: 0x15db9e80>; userInfo = {}}

Received notification: NSConcreteNotification 0x15d6a050 {name = ALAssetsLibraryChangedNotification; object = <ALAssetsLibrary: 0x15db9e80>; userInfo = {}}

Received notification: NSConcreteNotification 0x15d379e0 {name = ALAssetsLibraryChangedNotification; object = <ALAssetsLibrary: 0x15db9e80>; userInfo = {
ALAssetLibraryUpdatedAssetGroupsKey = "{(\n    assets-library://group/?id=1E76AFA7-89B4-4277-A175-D7C8E62E49D0&filter=1,\n    assets-library://group/?id=1E76AFA7-89B4-4277-A175-D7C8E62E49D0\n)}";
ALAssetLibraryUpdatedAssetsKey = "{(\n    assets-library://asset/asset.JPG?id=FBDD2086-EC76-473F-A23E-4F4200C0A6DF&ext=JPG\n)}";

Received notification: NSConcreteNotification 0x15df7bf0 {name = ALAssetsLibraryChangedNotification; object = <ALAssetsLibrary: 0x15db9e80>; userInfo = {
ALAssetLibraryUpdatedAssetGroupsKey = "{(\n    assets-library://group/?id=8E390051-E107-42BC-AE55-24BA35966642\n)}";}}

Received notification: NSConcreteNotification 0x15d40360 {name = ALAssetsLibraryChangedNotification; object = <ALAssetsLibrary: 0x15db9e80>; userInfo = {
ALAssetLibraryUpdatedAssetsKey = "{(\n    assets-library://asset/asset.JPG?id=5A45779A-C3C1-4545-9BD6-88F094FFA5B9&ext=JPG\n)}";}}

? , , , , . - ? , , .

, , (, , , , , , ):

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    UIImage *originalImage, *editedImage, *imageToSave;
    editedImage = (UIImage *) [info objectForKey:UIImagePickerControllerEditedImage];
    originalImage = (UIImage *) [info objectForKey:UIImagePickerControllerOriginalImage];
    if (editedImage) {
        imageToSave = editedImage;
    }else {
        imageToSave = originalImage;
    }

    // Get group/asset library/album
    __block ALAssetsGroup* groupToAddTo;
    ALAssetsLibrary *assetsLibrary = [ProfileViewController defaultAssetsLibrary];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:ALAssetsLibraryChangedNotification object:nil];

    [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
    if ([[group valueForProperty:ALAssetsGroupPropertyName] isEqualToString:albumName]) {
        NSLog(@"found album %@", albumName);
        groupToAddTo = group;

        // save to album
        CGImageRef img = [imageToSave CGImage];

        // There some orientation stuff here I pulled out for brevity sake 

        [assetsLibrary writeImageToSavedPhotosAlbum:img orientation: alOrientation completionBlock:^(NSURL* assetURL, NSError* error) {
            if (error.code == 0) {
                [assetsLibrary assetForURL:assetURL resultBlock:^(ALAsset *asset) {
                // assign the photo to the album
                    if ([groupToAddTo valueForProperty:ALAssetsGroupPropertyURL] == nil){
                        NSLog(@"group properties are nil!");
                    }else {
                        if([groupToAddTo addAsset:asset]){
                            // If the asset writes to the library, listen for the notification
                            [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleAssetChangedNotifiation:) name:ALAssetsLibraryChangedNotification object:nil];
                        }else {
                            NSLog(@"Image Not Added!");
                        }
                    }
                }
                failureBlock:^(NSError* error) {
                    NSLog(@"failed to retrieve image asset:\nError: %@ ", [error localizedDescription]);
                }];
            }else {
                NSLog(@"saved image failed.\nerror code %i\n%@", error.code, [error localizedDescription]);
            }
        }];
    }}
    failureBlock:^(NSError* error) {
        NSLog(@"failed to enumerate albums:\nError: %@", [error localizedDescription]);}];

    [picker dismissViewControllerAnimated:YES completion:NULL];
}