I want to stop/cancel the operation in case of running the request again. Method cancelAllHTTPOperationsWithMethod is working ok, but i have a problem when AFNetworking has already fetched the results and my successBlock is being fired - I want to stop it in the nearest future. But the problem is that operation.isCancelled is not cancelled.
The question is do i have to perform my 'very long successBlock' in NSOperation and cancel them too or is there any easier and faster method?
Code:
[[AFHTTPClient sharedInstance] cancelAllHTTPOperationsWithMethod:#"GET" path:#"path"];
[[AFHTTPClient sharedInstance] getPath:#"path" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void) {
for (longLoop) {
// do something long
if (self.isCancelled) return; // this won't fire no matter how often i run it
}
});
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
// do something to fail
}];
I've ended with doing NSOperation inside. Something like:
[[AFHTTPClient sharedInstance] cancelAllHTTPOperationsWithMethod:#"GET" path:#"path"];
[operationQueue cancelAllOperations];
[[AFHTTPClient sharedInstance] getPath:#"path" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
// add new operation
MyOperation *successOperation = [[MyOperation alloc] init];
[successOperation setResponseObject:responseObject];
[operationQueue addOperation:successOperation];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
// call delegate
[self didFailFetchDataWithError:error];
}];
Related
My scene is like this, first I have a server json api which return some data for specify page, the api is like /data/page/1. For this case, suppose the response data is :
page 1 => ['a','b']
page 2 => ['c','d']
page 3 => ['e','f']
I use AFNetworking 2 to fetch data from api, for single page data request it works well.
The problem is now I want to implement parallel request for more than one page. I need one api for view controller which accept one pages number, and callback with all data for these pages collected. The api I need is:
typedef void (^DataBlock)(id data);
- (void) dataForPages:(NSInteger)pages withSuccessBlock:(DataBlock)block;
If view controller pass 3 for pages parameter, I want AFNetworking can request data parallel and then collected the 3 result then use in callback block.
I tried to use NSOperationQueue to process multi AFHTTPRequestOperation but failed, the code demo is like this:
- (void) dataForPages:(NSInteger)pages withSuccessBlock:(DataBlock)block
{
//want to use for each, here suppose pages is 3
NSMutableArray *result = [[NSMutableArray alloc] init];
AFHTTPRequestOperation *op1 = [[AFHTTPRequestOperation alloc] initWithRequest:#"/data/page/1"];
AFHTTPRequestOperation *op2 = [[AFHTTPRequestOperation alloc] initWithRequest:#"/data/page/2"];
AFHTTPRequestOperation *op3 = [[AFHTTPRequestOperation alloc] initWithRequest:#"/data/page/3"];
[op1 setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
[result addObjectsFromArray: responseObject]; //responseObject is ['a', 'b']
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
}];
[op2 setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
[result addObjectsFromArray: responseObject]; //responseObject is ['c', 'd']
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
}];
[op3 setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
[result addObjectsFromArray: responseObject]; //responseObject is ['e', 'f']
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
}];
NSOperationQueue *q = [[NSOperationQueue alloc] init];
[q addOperation:op1];
[q addOperation:op2];
[q addOperation:op3];
[q waitUntilAllOperationsAreFinished];
block(result);
}
In my test the result always empty, I'm not quite understand waitUntilAllOperationsAreFinished.
Anyone knows how to deal this problem with NSOperation or GCD?
After some code research, I found it's difficult to get what I want with NSOperation and NSOperationQueue, because AFNetworking has it's own completion block handler.
The final solution is use dispatch_group, all code is like this:
dispatch_group_t group = dispatch_group_create();
NSURLRequest *req1 = ...;
NSURLRequest *req2 = ...;
AFHTTPRequestOperation *op1 = [[AFHTTPRequestOperation alloc] initWithRequest:req1];
AFHTTPRequestOperation *op2 = [[AFHTTPRequestOperation alloc] initWithRequest:req2];
NSMutableArray *result = [[NSMutableArray alloc] init];
dispatch_group_enter(group); //enter group
[op1 setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
[result addObjectsFromArray: responseObject];
dispatch_group_leave(group); //leave group in completion handler
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
dispatch_group_leave(group);
}];
dispatch_group_enter(group);
[op2 setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
[result addObjectsFromArray: responseObject];
dispatch_group_leave(group);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
dispatch_group_leave(group);
}];
[op1 start];
[op2 start];
dispatch_group_notify(group, dispatch_get_main_queue(), ^{
block(result);
});
I have this bool method that returns a yes or no for an inputted string.
I'm successfully able to return a YES or a NO, but I cannot seem to able to make a network connection and return a YES or a NO depending on the server's response.
I tried using __block and I don't feel like that will wait for the web request to finish, is there a way to return YES or NO in the success block without it giving me the error:
Incompatible block pointer types sending 'BOOL(^)(NSURLSessionTask*__strong, NSError __strong' to parameter of the type 'void(^)(NSURLSessionTask...)
-(BOOL)customResponseForString:(NSString *)text {
__block BOOL response_available;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
manager.responseSerializer = [AFHTTPResponseSerializer serializer];
[manager.responseSerializer setAcceptableContentTypes:[NSSet setWithObject:#"text/plain"]];
[manager GET:[NSString stringWithFormat:#"http://example.com/response.php?input=%#", text] parameters:nil success:^(NSURLSessionDataTask *task, id responseObject) {
NSDictionary *response = [NSJSONSerialization JSONObjectWithData:responseObject options:NSUTF8StringEncoding error:nil];
response_available = (BOOL)response[#"response_available"];
if (response_available) {
[session sendTextSnippet:response[#"response"] temporary:NO scrollToTop:NO dialogPhase:#"Summary"];
} else {
response_available = NO;
}
[session sendTextSnippet:[[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding] temporary:NO scrollToTop:NO dialogPhase:#"Summary"];
[session sendRequestCompleted];
} failure:^(NSURLSessionDataTask *task, NSError *error) {
//return NO;
}];
});
return response_available;
}
Your block definition syntax is probably erroneous, because you can definitely return a BOOL along other parameters in a block.
- (void)fetchCurrentUserWithCompletion:(void (^)(BOOL success, User *user))completion;
This method would be called like this:
[self.userProfileController fetchCurrentUserWithCompletion:^(BOOL success, User *user) {
if (success) {
NSLog(#"Current User Name: %#", user.fullName);
}
}];
If you use AFNetworking, check the AFHTTPRequestOperation object that handle completionBlocks:
[requestOperation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
User *user = [self userFromResponseObject:responseObject];
if (completion) completion(YES, user);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
if (completion) completion(NO, user);
}];
Because you are implicitly initializing response_available to NO and then using an async GCD call, your method as written will always immediately return NO without waiting for the request to finish. Note: switching to dispatch_sync won't help either because AFNetworking will queue the GET request asynchronously either way.
Best Approach
Add a completion block argument to customResponseForString:. Then simply execute your completion block in the success or failure blocks of the AFHTTPRequestOperation.
Workable Approach (use caution!)
It is possible to make customResponseForString: wait for a response to the network request, but you will have significant issues if it is ever called from the main thread.
First you create a dispatch group and tell it you are starting some long-running work:
dispatch_group_t networkGroup = dispatch_group_create();
dispatch_group_enter(networkGroup);
Then you need to make your network request and when it completes tell the group that the work is finished with dispatch_group_leave():
[manager GET:[NSString stringWithFormat:#"http://example.com/response.php?input=%#", text] parameters:nil success:^(NSURLSessionDataTask *task, id responseObject) {
NSDictionary *response = [NSJSONSerialization JSONObjectWithData:responseObject options:NSUTF8StringEncoding error:nil];
response_available = (BOOL)response[#"response_available"];
if (response_available) {
[session sendTextSnippet:response[#"response"] temporary:NO scrollToTop:NO dialogPhase:#"Summary"];
} else {
response_available = NO;
}
[session sendTextSnippet:[[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding] temporary:NO scrollToTop:NO dialogPhase:#"Summary"];
[session sendRequestCompleted];
dispatch_group_leave(networkGroup);
} failure:^(NSURLSessionDataTask *task, NSError *error) {
response_available = NO;
dispatch_group_leave(networkGroup);
}];
Before your original method returns, tell it to wait for the entire group to finish processing:
dispatch_group_wait(networkGroup, DISPATCH_TIME_FOREVER);
return response_available;
You could adjust this time interval as needed or leave it at DISPATCH_TIME_FOREVER to let the network request time out on its own.
On previous versions of AFNetworking I could make use of AFHTTPRequestOperation to create multiple requests, create dependencies between them and enqueue them pretty easily. Example (inside of an AFHTTPClient subclass):
NSURLRequest *categoriesRequest = [self requestWithMethod:#"GET" path:#"categories" parameters:nil];
AFHTTPRequestOperation *categoriesOperation = [self HTTPRequestOperationWithRequest:categoriesRequest success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSArray *jsonCategories = responseObject;
for (NSDictionary *jsonCategory in jsonCategories) {
SPOCategory *category = [[SPOCategory alloc] initWithDictionary:jsonCategory];
[self.categories addObject:category];
}
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
// …
}];
NSURLRequest *incidencesRequest = [self requestWithMethod:#"GET" path:#"incidences" parameters:nil];
AFHTTPRequestOperation *incidencesOperation = [self HTTPRequestOperationWithRequest:incidencesRequest success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSArray *jsonIncidences = responseObject;
for (NSDictionary *jsonIncidence in jsonIncidences) {
SPOIncidence *incidence = [[SPOIncidence alloc] initWithDictionary:jsonIncidence];
[self.incidences addObject:incidence];
}
completionBlock(self.incidences, self.categories, nil);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
// …
}];
[incidencesOperation addDependency:categoriesOperation];
[self enqueueBatchOfHTTPRequestOperations:#[categoriesOperation, incidencesOperation] progressBlock:^(NSUInteger numberOfFinishedOperations, NSUInteger totalNumberOfOperations) {
// Processing…
} completionBlock:^(NSArray *operations) {
// Completed
}];
I know I can continue to make use of AFHTTPRequestOperation but, I'd like to know if there is a similar way to achieve the same thing inside a subclass of AFHTTPSessionManager, using NSURLSession as the backing library instead of NSURLConnection.
Thank you!
AFHTTPSessionManager's connection factory methods create connections which will be represented by a NSURLSessionDataTask object.
Unlike AFHTTPRequestOperation these are not NSOperation subclasses, and thus declaring dependencies is not possible.
One could imagine to wrap a factory method like
- (NSURLSessionDataTask *)GET:(NSString *)URLString
parameters:(NSDictionary *)parameters
success:(void (^)(NSURLSessionDataTask *task, id responseObject))success
failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure;
into a helper method/function which returns a NSOperation object. That might (will) become cumbersome and looks quite weird, though.
If you are courageous enough to consider another third party library, you can solve your problem as explained below:
The idea is to represent the eventual result of the asynchronous operation by a "Promise". Think of a Promise as a placeholder of the result, which will eventually be set by the operation. So, basically you wrap a factory method into one which then effectively yields a method having this signature:
-(Promise*) fetchCategories;
or
-(Promise*) fetchCategoriesWithParameters:(NSDictionary*)parameters;
Notice that above methods are asynchronous - yet they have no completion handler. The Promise will instead provide this facility.
Initially, when fetchCategories returns, the promise object does not "contain" the result.
You obtain (at some tme later) the eventual result respectively and error by "registering" a completion handler block respectively an error handler block with a then property like so (pseudo code):
[self.fetchCategoriesWithParameters].then(
<success handler block>,
<failure handler block> );
A more complete code snippet:
Promise* categoriesPromise = [self fetchCategories];
categoriesPromise.then(^id(id result){
self.categories = result;
... // (e.g, dispatch on main thread and reload table view)
return nil;
}, ^id(NSError* error){
NSLog(#"Error: %#", error);
return nil;
});
Note: The parameter result of the success handler block is the eventual result of the operation, aka the responseObject.
Now, in order to "chain" multiple asynchronous operations (including the handlers), you can do this:
self.categoriesPromise = [self fetchCategories];
Promise* finalResult = self.categoriesPromise.then(^id(id result){
NSArray *jsonCategories = result;
for (NSDictionary *jsonCategory in jsonCategories) {
SPOCategory *category = [[SPOCategory alloc] initWithDictionary:jsonCategory];
[self.categories addObject:category];
}
return [self fetchIncidencesWithParams:result);
}, nil)
.then(^id(id result){
NSArray *jsonIncidences = result;
for (NSDictionary *jsonIncidence in jsonIncidences) {
SPOIncidence *incidence =
[[SPOIncidence alloc] initWithDictionary:jsonIncidence];
[self.incidences addObject:incidence];
}
return #[self.incidences, self.categories];
}, nil)
.then(^id(id result){
NSArray* incidences = result[0];
NSArray* categories = result[1];
...
return nil;
}, nil /* error handler block */);
You create and "resolve" (that is, setting the result) a Promise as shown below:
- (Promise*) fetchCategories {
Promise* promise = [[Promise alloc] init];
NSURLRequest *categoriesRequest = [self requestWithMethod:#"GET" path:#"categories" parameters:nil];
AFHTTPRequestOperation *categoriesOperation = [self HTTPRequestOperationWithRequest:categoriesRequest success:^(AFHTTPRequestOperation *operation, id responseObject) {
[promise fulfillWithResult:responseObject];
}
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
[promise rejectWithReason:error];
}];
return promise;
}
Disclaimer:
There are a few third party Objective-C libraries which implement a Promise in this or a similar way. I'm the author of RXPromise which implements a promise according the Promises/A+ specification.
The following code using AFNetworking 2.0 is valid to fetch data through internet:
NSString *URLPath = #"http://www.raywenderlich.com/downloads/weather_sample/weather.php?format=json";
NSDictionary *parameters = nil;
[[AFHTTPRequestOperationManager manager] GET:URLPath parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(#"success: %#", responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"failure: %#", error);
}];
But I want to test those requests synchronously in the unit test. But it would be blocked when using GCD semaphore like this:
// This code would be blocked.
dispatch_semaphore_t sema = dispatch_semaphore_create(0);
NSString *URLPath = #"http://www.raywenderlich.com/downloads/weather_sample/weather.php?format=json";
NSDictionary *parameters = nil;
[[AFHTTPRequestOperationManager manager] GET:URLPath parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(#"success: %#", responseObject);
dispatch_semaphore_signal(sema);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"failure: %#", error);
dispatch_semaphore_signal(sema);
}];
dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);
dispatch_release_ARC_compatible(sema);
How can I fetch data using AFNetworking 2.0 library synchronously (test those code in Kiwi)?
Your semaphore would be blocked because by default AFNetworking runs on the main loop. So if you're waiting on the main loop for the semaphore, AFNetworking's code never gets to run.
In order to fix this, you simply have to tell AFNetworking to use a different dispatch queue. You do that by setting the operationQueue property on AFHTTPRequestOperationManager
You can create your own dispatch queue, or use one of the predefined ones, like so:
// Make sure that the callbacks are not called from the main queue, otherwise we would deadlock
manager.operationQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
I am trying out afnetworking 2.0 and just trying to figure out how to cancel specific tasks.
The old way would be to use something like
[self cancelAllHTTPOperationsWithMethod:#"POST" path:#"user/receipts"]
but I dont see anything like this in 2.0
I created a sub class of AFHTTPSessionManager which gives me access to the array of pending tasks and I can cancel them directly but I dont know how to identify 1 task from another so I can cancel only specific tasks.
Task does have an taskidentifier but this doesnt appear to be what I need.
NSString *path = [NSString stringWithFormat:#"user/receipts"];
[self.requestSerializer setAuthorizationHeaderFieldWithUsername:[prefs valueForKey:#"uuid"] password:self.store.authToken];
[self GET:path parameters:nil success:^(NSURLSessionDataTask *task, id responseObject) {
completionBlock(responseObject);
} failure:^(NSURLSessionDataTask *task, NSError *error) {
errorBlock(error);
}];
now if i wanted to cancel this request only how would I approach this?
You can store the task in a variable so you can access it later:
NSURLSessionDataTask* task = [self GET:path parameters:nil success:^(NSURLSessionDataTask *task, id responseObject) {
completionBlock(responseObject);
} failure:^(NSURLSessionDataTask *task, NSError *error) {
errorBlock(error);
}];
Then simply cancel it with [task cancel].
Another way would be to save the task ID of the task and later ask the URL session for its tasks and identify the task you wish to cancel:
// save task ID
_savedTaskID = task.taskIdentifier;
// cancel specific task
for (NSURLSessionDataTask* task in [self dataTasks]) {
if (task.taskIdentifier == _savedTaskID) {
[task cancel];
}
}
No need to save it, here is my implementation, use your subclass of AFURLSessionManager for cancelling specific request:
- (void)cancelAllHTTPOperationsWithPath:(NSString *)path
{
AFURLSessionManager * yourSessionManager = [self getSessionManager];
[[yourSessionManager session] getTasksWithCompletionHandler:^(NSArray *dataTasks, NSArray *uploadTasks, NSArray *downloadTasks) {
[self cancelTasksInArray:dataTasks withPath:path];
[self cancelTasksInArray:uploadTasks withPath:path];
[self cancelTasksInArray:downloadTasks withPath:path];
}];
}
- (void)cancelTasksInArray:(NSArray *)tasksArray withPath:(NSString *)path
{
for (NSURLSessionTask *task in tasksArray) {
NSRange range = [[[[task currentRequest]URL] absoluteString] rangeOfString:path];
if (range.location != NSNotFound) {
[task cancel];
}
}
}
you can do the following
NSArray *operations = [[[MyClient sharedClient] operationQueue] operations];
if(operations && operations.count > 0){
for (NSOperation *operation in operations) {
if([operation isKindOfClass:[AFHTTPRequestOperation class]]){
AFHTTPRequestOperation *httpOperation = (AFHTTPRequestOperation *)operation;
NSLog(#"%#", [[httpOperation request] URL]);
//--- if this is your request then cancel it --> [httpOperation cancel];
}
}
}
Where MyClient is a child of AFHTTPClient and the function sharedClient is a static function which returns a singleton instance of MyClient