I am implementing a code that downloads images and saves them in the database of the app,
I have an array of objects, each object contains the image url and some other information. To Download the images I'm using the class library AFImageRequestOperation.h AFNetworking.
My code downloads and saves the data in the database, but need to notify the user which image is downloaded, eg: if I have an array containing 5 objects (quoted just above what each object), will have to do downloading the same order that is in the array, but as AFImageRequestOperation makes downloading asynchronously item 4 can be downloaded before the first item.
In short, I want to have control and only release for the next download when the previous one is completed.
I have a for that runs through the array of objects and calls a function for each position, the function has the following code:
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:[arrImagem valueForKey:#"urlimagem"]]];
AFImageRequestOperation *operation = [AFImageRequestOperation imageRequestOperationWithRequest:request imageProcessingBlock:nil success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image){
Imagens *imagem = (Imagens *)[NSEntityDescription insertNewObjectForEntityForName:#"IMAGENS" inManagedObjectContext:managedObjectContext];
// Save Image
NSData *imageData = UIImageJPEGRepresentation(image, 90);
[imagem setCategoria:cat];
[imagem setTitulo:[arrImagem valueForKey:#"titulo"]];
[imagem setDescricao:[arrImagem valueForKey:#"descricao"]];
[imagem setImagem:imageData];
NSError *error;
if(![managedObjectContext save:&error]){
NSLog(#"houve um erro muito grave");
//return false;
}else{
NSLog(#"Salvou imagem");
}
}failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error){
NSLog(#"%#", [error localizedDescription]);
}];
[operation start];
I do not know if my question was very clear, but basically my question is similar to this link
AFImageRequestOperation is a subclass of NSOperation so you can use:
- (void) addDependency: (NSOperation*) operation
to make sure that one operation finishes before the other.
For example:
NSOperation *op1 = [[NSOperation alloc]init];
NSOperation *op2 = [[NSOperation alloc]init];
[op1 addDependency: op2];
This way op1 won't start before op2 is finished.
You can create a method in your class where you call the download code and add a block as parameter which receives the downloaded UIImage, the image url (and other infos that you need) or you can implement a delegate with the same params from the block. It can lock something like:
-(void)downloadImageWithSuccess:(void (^)(UIImage *image, NSString *url, OtherParms here))success
failure:(void (^)(NSError *error)failure {
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:[arrImagem valueForKey:#"urlimagem"]]];
AFImageRequestOperation *operation = [AFImageRequestOperation imageRequestOperationWithRequest:request imageProcessingBlock:nil success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image){
Imagens *imagem = (Imagens *)[NSEntityDescription insertNewObjectForEntityForName:#"IMAGENS" inManagedObjectContext:managedObjectContext];
// Save Image
NSData *imageData = UIImageJPEGRepresentation(image, 90);
[imagem setCategoria:cat];
[imagem setTitulo:[arrImagem valueForKey:#"titulo"]];
[imagem setDescricao:[arrImagem valueForKey:#"descricao"]];
[imagem setImagem:imageData];
NSError *error;
if(![managedObjectContext save:&error]){
NSLog(#"houve um erro muito grave");
//return false;
}else{
NSLog(#"Salvou imagem");
}
success(imagem, [request.URL absoluteString], otherParams);
}failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error){
NSLog(#"%#", [error localizedDescription]);
failure(error);
}];
[operation start];
}
}
And when you call the method from your code you can do something like(using blocks):
[catalog downloadImageWithSuccess:^(UIImage *image, NSString *url, OtherParms here) {
//NOTIFY USER THAT THE IMAGE WITH URL HAS BEEN DOWNLOADED
}
failure:^(NSError *error) {
//NTOFIY USER THAT THE IMAGE FAILED
}
];
managed to solve my problem, sorry for the delay in posting the solution, follow the code below:
dispatch_group_t group = dispatch_group_create();
dispatch_group_enter(group);
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:strUrl]];
AFImageRequestOperation *operation = [AFImageRequestOperation imageRequestOperationWithRequest:request imageProcessingBlock:nil success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image){
//your implementation
dispatch_group_leave(group); //<== NOTICE THIS
}failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error){
//your implementation
NSLog(#"%#", [error localizedDescription]);
}];
[operation start];
dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
Thus the downloads ocorerão in order, if this code is inside a case, the next download will only be called when the method success^: or failure^: is called
Related
So I am working on a project and I must use AFImageDownloader in order to download some images that we need to use in our project. I use the following code:
-(void) downloadImage:(NSURL*) url
{
AFHTTPSessionManager *sessionManager = [[AFHTTPSessionManager alloc] init];
AFImageDownloader *imgDownloader = [[AFImageDownloader alloc] initWithSessionManager:sessionManager downloadPrioritization:AFImageDownloadPrioritizationFIFO maximumActiveDownloads:1 imageCache:nil];
AFHTTPResponseSerializer *responseSerializer = [AFHTTPResponseSerializer serializer];
responseSerializer.acceptableContentTypes = [NSSet setWithObjects:#"application/json", #"text/json",#"binary/octet-stream",nil];
sessionManager.responseSerializer = responseSerializer;
NSURLRequest *req = [NSURLRequest requestWithURL:url];
[imgDownloader downloadImageForURLRequest:req success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *responseObject){
self.image = responseObject;
[self.delegate updateImageWithImage:self.image]; // ** CRASH **
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error){
NSLog(#"Error");
}];
}
The delegate is of course not nil and code of the updateImageWithImage is:
-(void) updateImageWithImage:(UIImage*) img {
self.image.image = img;
}
So basically when I try to get the UIImage I get it as a response and assign it to the UICollectionViewCell and it crashes! I guess that I should do some kind of "copy" of the responseObject before using it in order parts of my program, but I am not really sure what the problem is. Any ideas?
I figured it out. I was basically using AFImagedownloader wrong, this is the proper way to use this Class:
[self.imageView setImageWithURLRequest:jpegURLRequest
placeholderImage:placeholder
success:^(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, UIImage *image){
NSLog(#"Success");
completionBlock(image);
}
failure:^(NSURLRequest * _Nonnull request, NSHTTPURLResponse * _Nullable response, NSError * _Nonnull error) {
NSLog(#"ERROR!!!");
}];
When the operation is running, I can not enter data in JSON model CREATED BY ACCELERATOR.
Can you tell me what I am doing wrong?
{
[super viewDidLoad];
NSLog(#"you are in a tableViewController");
self.title = #"NavigationOrdini";
NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:#"http://www.stampa6x3.com/json.php?azione=ordini"]];
AFJSONRequestOperation* operation;
operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:req
success:^(NSURLRequest *request, NSURLResponse *response, id JSON)
{
[[ordiniModel alloc] initWithDictionary:JSON];
}
failure:^(NSURLRequest *request, NSURLResponse *response, NSError
*error, id JSON) {
[self setTitle:#"Dictionary"];
NSLog(#"failed! %d",[error code]);
}];
[operation start];
ordiniModel*test;
NSLog(#"il valore è %#",test.ordini.description);
}
AFJSONRequestOperation is asynchronous, meaning it that the code continues to execute while the rest of the app runs. The completion block are run when the code actually completes.
So try:
NSLog(#"you are in a tableViewController");
self.title = #"NavigationOrdini";
ordiniModel *test; // <-- create variable here
NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:#"http://www.stampa6x3.com/json.php?azione=ordini"]];
AFJSONRequestOperation* operation;
operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:req
success:^(NSURLRequest *request, NSURLResponse *response, id JSON)
{
test = [[ordiniModel alloc] initWithDictionary:JSON]; // <-- Assign here
NSLog(#"il valore è %#",test.ordini.description);
}
failure:^(NSURLRequest *request, NSURLResponse *response, NSError
*error, id JSON) {
[self setTitle:#"Dictionary"];
NSLog(#"failed! %d",[error code]);
}];
[operation start];
I am trying to add a Success and Error block to check when the image is loaded so that I can use NSCache to dynamically resize the image. But when I try
[scribbleImage setImageWithURL: [NSURL URLWithString:scribble[#"scribble_image"]] placeholderImage:[UIImage imageNamed:#"Default.png"] success:^(UIImage *image) {
NSLog(#"done");
} failure:^(NSError *error) {
NSLog(#"error %#",error);
}];
Xcode gives me an error, saying No visible #interface for 'UIImageView' declares the selector 'setImageWithURL:placeholderImage:success:failure:'
I am not sure why.
PS. I am importing UIImageView+AFNetworking.h and things work just fine without a success and failure block
This is because the there is no method setImageWithURL:placeholderImage:success:failure: there is just setImageWithURLRequest:placeholderImage:success:failure:
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:scribble[#"scribble_image"]]];
[scribbleImage setImageWithURLRequest:request placeholderImage:[UIImage imageNamed:#"Default.png"] success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
NSLog(#"Done");
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
NSLog(#"Failed with error: %#", error);
}];
If you look at what setImageWithURL:placeholderImage: does :
- (void)setImageWithURL:(NSURL *)url
placeholderImage:(UIImage *)placeholderImage
{
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPShouldHandleCookies:NO];
[request addValue:#"image/*" forHTTPHeaderField:#"Accept"];
[self setImageWithURLRequest:request placeholderImage:placeholderImage success:nil failure:nil];
}
You see that this is the method is used to fetch the internally as well.
I'm relatively new to AFNetworking and would like to find a better solution for the following problem.
I am using 2 AFJSONRequestOperations at the start of my iOS application.
AFJSONRequestOperation *operation1 = [AFJSONRequestOperation JSONRequestOperationWithRequest:request1 success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
// do something
}failure:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON, NSError *error){
// do something
}];
AFJSONRequestOperation *operation2 = [AFJSONRequestOperation JSONRequestOperationWithRequest:request2 success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
// do something
}failure:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON, NSError *error) {
// do something
}];
[operation1 start];
[operation2 start];
I wait for both operations to finish and start further processing.
I thought I can combine both of this operations into the enqueueBatchOfHTTPRequestOperationsWithRequests method.
AFHTTPClient *client = [[AFHTTPClient alloc] init];
NSArray *requests = [NSArray arrayWithObjects:operation1, operation2, nil];
[client enqueueBatchOfHTTPRequestOperationsWithRequests:requests progressBlock:^(NSUInteger numberOfFinishedOperations, NSUInteger totalNumberOfOperations) {
// track operations
}completionBlock:^(NSArray *operations) {
// do something
}];
So I would like to track the finished operations and execute the completion block for each operation separatly. Is it something I can perform with AFHTTPClient?
I have found a way to queue JSON parsing operation to wait complete data parse, and this is the code:
- (void)LoadParse { // this method is called by a UIButton
NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData timeoutInterval:5.0];
AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
// PARSING SUCCESS CODE
NSLog(#"operation completed"); <--- END OPERATION
[self anotherMethod]; <--- CALL METHOD AFTER OPERATION IS FINISHED
}
failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON {
// PARSING FAILURE CODE
}];
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[queue addOperation:operation]; <--- START OPERATION
// I NEED TO SHOW A SORT OF INDICATOR TO ADVERT USER THAT OPERATION ARE STILL LOADING
// EXAMPLE: [DejalBezelActivityView activityViewForView:self.view withLabel:#"LOADING..."].showNetworkActivityIndicator = YES;
[queue waitUntilAllOperationsAreFinished];
}
The queue works perfectly: app waits the end of parsing operation, then it calls anotherMethod. But I need to show a sort of activityView to advert user when there is still loading operation: as u can see I've tried to add it between addOperation and waitUntilAllOperationsAreFinished but I cant see anything. IS IT THE RIGHT WAY? So, where is the RIGHT place to put activityView code to view it Until All Operations Are Finished, or another way to do that trick? Thanks!
Can use this code
- (void)LoadParse { // this method is called by a UIButton
NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData timeoutInterval:5.0];
AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
// PARSING SUCCESS CODE
}
failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON {
// PARSING FAILURE CODE
}];
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[queue addOperation:operation];
UIActivityIndicatorView *tempSpinner = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
[self.view addSubview:tempSpinner];
[tempSpinner startAnimating];
[queue waitUntilAllOperationsAreFinished];
[tempSpinner stopAnimating];
//release tempSpinner if not using arc using [tempSpinner release];
[self anotherMethod];
}