I'm using writeImageToSavedPhotosAlbum:orientation:completionBlock: to save an image and it's ok. Then I want an array of assets in the Album.
The first time I refresh my array it doesn't count the new image, while calling it a second time it works fine.
Why? I understand that the writeImageToSavedPhotosAlbum start another thread and that the Block is called after the save operation completes, isn't it?
This is the code I use to save the image and refresh my array:
[_album refresh];
ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];
[library writeImageToSavedPhotosAlbum:image
metadata:metadataAsMutable
completionBlock:^(NSURL *assetURL, NSError *error) {
if (error) {
NSLog(#"ERROR: the image failed to be written");
}
else {
NSLog(#"PHOTO SAVED - assetURL: %#", assetURL);
}
[_album refresh];
[_album refresh];
[spinner stopAnimating];
[self close];
}];
This is the refresh function:
- (void)refresh {
[_imgAssets removeAllObjects];
if (_albumGroup) {
[_albumGroup enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {
if(result == nil) {
NSLog(#"done enumerating photos (%d)", [_imgAssets count]);
return;
}
[_imgAssets addObject:result];
//NSLog(#">> enumerating photos (%d)", [_imgAssets count]);
}];
}
}
And this is what I obtain:
2013-06-04 23:19:07.962 PhotInfo[4835:c07] done enumerating photos (29)
2013-06-04 23:19:08.041 PhotInfo[4835:c07] PHOTO SAVED - assetURL: assets-library://asset/asset.JPG?id=CDC2E97A-FF47-4A52-99E2-574037155D92&ext=JPG
2013-06-04 23:19:08.042 PhotInfo[4835:c07] done enumerating photos (29)
2013-06-04 23:19:08.044 PhotInfo[4835:c07] done enumerating photos (30)
Moreover, if I replace the second of the 3 refresh with
[_album performSelectorOnMainThread:#selector(refresh) withObject:nil waitUntilDone:YES];
it may or may not read the added image.
Where is the problem?
Thanks for the help.
I've resolved setting an observer on ALAssetsLibraryChangedNotification.
Related
I'm looking for help with trying to update a progress indicator using the MRProgress framework. I was able to set up the progress indicator, but I have no idea how to calculate and update its progress. I'm using CloudKit and trying to show the progress when saving a CKRecord. Could someone provide me some direction? Thanks in advance!
self.hud = [MRProgressOverlayView showOverlayAddedTo:self.myCollectionView animated:YES];
self.hud.mode = MRProgressOverlayViewModeDeterminateCircular;
self.hud.titleLabelText = #"Uploading...";
// prepare the CKRecord and save it
[self.ckManager saveRecord:[self.ckManager createCKRecordForImage:self.imageDataAddedFromCamera] withCompletionHandler:^(CKRecord *record, NSError *error) {
if (!error && record) {
NSLog(#"INFO: Record saved successfully for recordID: %#", record.recordID.recordName);
// need to get the recordID of the just saved record before adding the CID to the CIDArray
self.imageDataAddedFromCamera.recordID = record.recordID.recordName;
[self.imageLoadManager addCIDForNewUserImage:self.imageDataAddedFromCamera]; // update the model with the new image
// update number of items since array set has increased from new photo taken
self.numberOfItemsInSection = [self.imageLoadManager.imageDataArray count];
//[MRProgressOverlayView dismissAllOverlaysForView:self.view animated:YES];
[self.hud dismiss:YES];
[self.hud removeFromSuperview];
} else {
NSLog(#"ERROR: Error saving record to cloud...%#", error.localizedDescription);
[self alertWithTitle:#"Yikes!" andMessage:#"We encountered an issue trying to upload your photo to the cloud."];
}
}];
Update: Converted cloudkit methods from convenience API to CKOperations in my CKManager class. I can see the progress updating through logging, but I don't see how to get it back to the viewcontroller. If I were to add it to the completion handler, wouldn't that only send it back once everything is completed? Here's my updated code...
CKManager.h
- (void)saveRecord:(NSArray *)records withCompletionHandler:(void (^)(NSArray *records))completionHandler;
CKManager.m
- (void)saveRecord:(NSArray *)records withCompletionHandler:(void (^)(NSArray *))completionHandler {
NSLog(#"INFO: Entered saveRecord...");
CKModifyRecordsOperation *saveOperation = [[CKModifyRecordsOperation alloc] initWithRecordsToSave:records recordIDsToDelete:nil];
saveOperation.perRecordProgressBlock = ^(CKRecord *record, double progress) {
if (progress <= 1) {
NSLog(#"Save progress is: %f", progress);
}
};
saveOperation.completionBlock = ^ {
NSLog(#"Save operation completed!");
completionHandler(records);
};
[self.publicDatabase addOperation:saveOperation];
}
if you want to show the progress of an operation, then you have to use the CKModifyRecordsOperation and use perRecordProgressBlock method.
I'm trying to enumerate through the ALAssetLibrary to retrieve all saved photos. From the enumeration block, I'm trying to to send each ALAsset for asynchronous processing by passing it to an NSInvocationOperation object, then adding that to an NSOperationQueue. However, only the first ALAsset object is properly passed to the processing method. All subsequent assets are just passed as nil.
Here is my code:
ViewDidLoad:
queue = [[NSOperationQueue alloc] init];
queue.maxConcurrentOperationCount = 1;
ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];
[library enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop)
{
[group setAssetsFilter:[ALAssetsFilter allPhotos]];
[group enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop)
{
if (! result) {
return;
}
NSInvocationOperation* operation = [[NSInvocationOperation alloc] initWithTarget:self selector:#selector(processAsset:) object:result];
[queue addOperation:operation];
return;
}];
} failureBlock:^(NSError *error) {
NSLog(#"%#", error);
}];
And the -processAsset method
- (void)processAsset:(ALAsset *)asset
{
NSLog(#"Asset: %#", asset);
// Asset is nil after the first iteration
}
Any help would be really appreciated, thanks!
All ALAssets objects are deallocated when the ALAssetsLibrary that obtained them goes out of scope. If you want to do what you're doing, you'll need to keep a strong reference to library, and then deallocate library when you're done with it.
(In your case, they deallocate at the end of viewDidLoad.)
I'm working on photo app and here is the deal:
I have created custom photo album an added some photos to it (users can create many albums). I used ALAssetsLibrary for this and CustomPhotoAlbum category. Everything worked flawlessly until I needed to get those photos back to reuse them.
So Ive created custom metod for this category and I'm saving UIImages to NSMutableArray but I want this method to return this array outside... My problem is that enumerateAssetsUsingBlock: is running in background and saving photos to album while I want to access them! How can I do something for this method to wait until every photo is loaded to album and then return NSArray?
Here is my method:
- (void)loadImagesFromAlbumNamed:(NSString *)name
{
NSMutableArray *photos = [[NSMutableArray alloc] init];
[self enumerateGroupsWithTypes:ALAssetsGroupAll
usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
if (group == nil) {
return;
}
if ([[group valueForProperty:ALAssetsGroupPropertyName] isEqualToString:name]) {
[group enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {
if (result == nil) {
return;
}
// NSLog(#"%#", result);
UIImage *image = [UIImage imageWithCGImage:(__bridge CGImageRef)([result defaultRepresentation])];
[photos addObject:image];
}];
NSLog(#"%#", [photos description]);
}
} failureBlock:^(NSError *error) {
NSLog(#"%#", [error localizedDescription]);
}];
}
I hope you get my point of view... If not, just ask and I'll try to explain it better way!
Don't try to wait. Instead, pass a block to your method which should be called when all of the asset processing blocks are completed and will pass the array of images back to the caller. The caller should not block, you just want to structure your method to deal with the asynchronous nature of what you're trying to do.
Struggling a bit here with blocks and the ALAssetLibrary routines. I've been through the WWDC + Stanford videos on blocks and read up a bit but it hasn't quite clicked for me yet.
What I am trying to do is get the posterImage for a custom photo library. The first routine below is in my main viewController and calls the function getPosterImageForAlbum: which is in an ALAssetLibrary class extension.
The things I am struggling with/confused about/have tried:
Should I pass in a reference (CGImageRef or UIImage) and have the
ALAssetLibrary method set it or define a return value for the
ALAssetLibrary method and then handle the image in my main class?
I've tried it both ways without success.
The asynchronous nature of the ALAssetLibrary enumeration methods are
kind of hard to work with - so I guess I am doing it wrong.
Defining a block to be passed as a param: do I always need to
typedef it?
I think I've got all the conceptual bits and pieces swirling around but I haven't yet been able to wrangle them into a clear understanding of working with blocks. Any tips or pointers* to good articles would be much appreciated.
//
- (IBAction)getPosterImage:(id)sender {
NSString *groupName = self.groupNameField.text;
NSLog(#"%#", groupName);
__weak typeof(self) weakSelf = self;
CGImageRef tmpImg = [weakSelf.library getPosterImageForAlbum:groupName withCompletionBlock:(CGImageRef)(^GetPosterImageCompletion)(NSError *error){
if (error!=nil) {
NSLog(#"getPosterImage error: %#", [error description]);
} else {
if (tmpImg != nil){
UIImage * posterImg = [UIImage imageWithCGImage:tmpImg];
weakSelf.pImage.image = posterImg;
}
}
}];
}
// This is in an extension of the ALAssetLibrary
typedef CGImageRef(^GetPosterImageCompletion)(NSError* error);
-(CGImageRef)getPosterImageForAlbum:(NSString*)albumName
withCompletionBlock:(GetPosterImageCompletion)completionBlock
{
__block BOOL albumWasFound = NO;
__block CGImageRef thePosterImage = nil;
SaveImageCompletion test;
//search all photo albums in the library
[self enumerateGroupsWithTypes:ALAssetsGroupAlbum
usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
NSLog(#"this group name: %#",
[group valueForProperty:ALAssetsGroupPropertyName]);
//compare the names of the albums
if ([albumName compare:
[group valueForProperty:ALAssetsGroupPropertyName]]==NSOrderedSame) {
printf("matches \n"); //target album is found
albumWasFound = YES;
thePosterImage = group.posterImage;
*stop = true;
return ;
}
} failureBlock: test];
if (albumWasFound==NO) {
NSLog(#"%#", #"No group found");
}
return thePosterImage;
}
I'm editing my original answer in a big way because only after I posted it did I really understand what you are trying to do -- write a class extension on ALAssetLibrary that finds an album's poster image by name, rather than just find an album's poster image by name in any way possible.
I would handle this by writing an extension method that takes, as a parameter, a completion block that accepts a single parameter of type UIImage (or optionally an NSError parameter as well). In that completion block, the caller can do whatever they want with the image that's asynchronously returned. There is no need to typedef the block -- you could write the method this way:
- (void) getPosterImageForAlbumNamed: (NSString *) albumName completionBlock: (void (^)(UIImage *, NSError *)) completionBlock
{
__block ALAssetsGroup * foundAlbum = nil;
[self enumerateGroupsWithTypes: ALAssetsGroupAlbum
usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
if (group) {
if ([(NSString *) [group valueForProperty: ALAssetsGroupPropertyName] compare: albumName] == NSOrderedSame) {
*stop = YES;
foundAlbum = group;
completionBlock([UIImage imageWithCGImage: [group posterImage]], nil);
}
} else{
if (! foundAlbum) {
NSLog(#"Album wasn't found");
// completionBlock(nil, XX SOME ERROR XX);
}
}
} failureBlock:^(NSError *error) {
NSLog(#"Couldn't access photo library");
// completionBlock(nil, XX SOME ERROR XX);
}];
}
Then, you could call the method this way:
-(IBAction) getPosterForAlbum: (id) sender
{
NSString * albumName = self.textField.text;
ALAssetsLibrary * library = [[ALAssetsLibrary alloc] init];
__weak typeof(self) weakSelf = self;
[library getPosterImageForAlbumNamed: albumName completionBlock:^(UIImage * image, NSError * error) {
if (! error) {
[weakSelf doSomethingWithPosterImage: image];
}
}];
}
Is that along the lines of what you are trying to do? (Sorry for the major edit...)
ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];
[library enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos
usingBlock:libraryGroupsEnumeration
failureBlock:failureblock];
ALAssetsGroupEnumerationResultsBlock groupEnumerAtion = ^(ALAsset *result, NSUInteger index, BOOL *stop){
if (result!=NULL) {
if ([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]) {
[self._dataArray addObject:result];
}
}
};
ALAssetsLibraryGroupsEnumerationResultsBlock
libraryGroupsEnumeration = ^(ALAssetsGroup* group, BOOL* stop){
//within the group enumeration block.filter to enumerate just photos.
[group setAssetsFilter:[ALAssetsFilter allPhotos]];
if (group!=nil) {
NSString *g=[NSString stringWithFormat:#"%#",group];
NSLog(#"gg:%#",g);//gg:ALAssetsGroup - Name:Camera Roll, Type:Saved Photos, Assets count:71
[group enumerateAssetsUsingBlock:groupEnumerAtion];
}
else {
dispatch_async(dispatch_get_global_queue(0, 0), ^{
[self saveToDB:self._dataArray];
});
}
};
Assume that my Camera Roll have 100 photos,and I want get first 30 to save to my database.but in above code ,I must wait for 100 results fisishing.After 30 write to database , continue to get another 30 until end.
because get 100 or even more photos will delay my UI refresh.It looks not comfortable.
Thanks a lot!
what should I write.?
Try this one
if (result!=NULL) {
if ([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]) {
[self._dataArray addObject:result];
if([self._dataArray count] == 30){
dispatch_async(dispatch_get_global_queue(0, 0), ^{
NSArray *array = [[NSArray alloc] initWithArray:self._dataArray]; //please change the array declaration to top of this method. Because the Block will not allow to do it here.
[self._dataArray removeAllObjects];
[self saveToDB:array];
//array release,if not using ARC
});
}
}
}
and
if (group!=nil) {
[group enumerateAssetsUsingBlock:groupEnumerAtion];
}
else if([self._dataArray count] > 0) {
dispatch_async(dispatch_get_global_queue(0, 0), ^{
[self saveToDB:self._dataArray];
});
}
You should try saving to the database on a background thread, and let CoreData (assuming you use CoreData) update the NSManagedObjectContext on the main thread by handling NSManagedObjectContextDidSaveNotification.
You could still save after 30 photos, that might relieve some of the I/O stress, but you'd have to test performance.