Multi part NSArray Post AFNetworking - ios

Question

I have a large NSArray I am wanting to split into chunks and send to my web server, upon completion of each chunk I then need to update the fields in my SQLite DB that relate to each item in each array chunk.
This is the code I am currently running, where I try to use a call back to receive success or failure then update my local SQLite DB where appropriate.
- (void)postlowData:(NSArray *)lowMArray Callback:(void (^)(NSError *error, BOOL success))callback;
{
// Currently this method is sending the whole lowMArray
// What I want to do is Split lowMArray into a chunkArray (where chunk is 20 of the leading items from lowMArray)
// I would then send chunkArray with the following code, when I receive a response I then want to update local SQLite DB with result and recall this method to start on the next 20 chunks.
// Create Json data from lowMArray
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:lowMArray
options:NSJSONWritingPrettyPrinted
error:nil];
// Construct post request
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:[NSString stringWithFormat:#"%#/lows", _silServerBaseUrl]]];
request = [self applyAuth:request];
[request setHTTPMethod:#"POST"];
[request setValue:#"application/json; charset=UTF-8" forHTTPHeaderField:#"Content-Type"];
[request setHTTPBody:jsonData];
// Send post request
AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
NSURLSessionDataTask *dataTask = [manager dataTaskWithRequest:request completionHandler:^(NSURLResponse *response, id responseObject, NSError *error) {
if (error) {
// NSLog(#"Response Failed!");
callback(error, NO);
} else {
// NSLog(#"Response Success!");
callback(error, YES);
// On success add itmes from lowChunkArray so that you can adjust sent_Flag later
}
}];
[dataTask resume]; // runs task
}
The issue I am running into is that when I run this code if I am splitting the array into chunks sending the chunk adjusting the main array for the next chunk I don't get a confirmed callback till the very end of all the requests, at which point I have lost track of what success or failure?
Maybe I am going about this the wrong way?
Update
I am now trying to do this using AFHTTPRequestOperation which seems to be working as a batch upload however the
setHTTPBody:jsonData
Never seems to make it to the server.
I used this Batch of Operations example to help me construct this method however as I said above the JSON data never makes it to the server.
- (void)postlowData:(NSArray *)lowMArray;
{
NSLog(#"Syncing Local");
NSArray *chunklow = [[NSArray alloc] init];
NSMutableArray *mutableOperations = [NSMutableArray array];
NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:#"%#/lows", _silServerBaseUrl]];
//Test: creating 10 things to send
for (int i = 0; i < 10; i++) {
if ([lowMArray count] > 0) {
if ([lowMArray count] >= 20) {
low = [lowMArray subarrayWithRange:NSMakeRange(0, 20)];
} else if ([lowMArray count] < 20) {
low = [lowMArray subarrayWithRange:NSMakeRange(0, [lowMArray count])];
}
}
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:low
options:NSJSONWritingPrettyPrinted
error:nil];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
request = [self applyAuth:request];
[request setHTTPMethod:#"POST"];
[request setValue:#"application/json; charset=UTF-8" forHTTPHeaderField:#"Content-Type"];
[request setHTTPBody:jsonData];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
[mutableOperations addObject:operation];
}
NSArray *operations = [AFURLConnectionOperation batchOfRequestOperations:mutableOperations progressBlock:^(NSUInteger numberOfFinishedOperations, NSUInteger totalNumberOfOperations) {
NSLog(#"%lu of %lu complete", numberOfFinishedOperations, totalNumberOfOperations);
} completionBlock:^(NSArray *operations) {
NSLog(#"All operations in batch complete");
NSLog(#"Syncing complete");
}];
[[NSOperationQueue mainQueue] addOperations:operations waitUntilFinished:NO];
}

Answer 1

For your problem of splitting insertion of a large array into chunks to be inserted to a DB via network operations, an NSOperationQueue can be created that will allow you to add a separate operation for each chunk of data to be inserted.
The queue can be set to run in a serial manner so that each operation will need to be complete before the next one is started.
Using a queue makes the multiple operations more manageable than having the flow be controlled by callbacks.
In summary, you create a queue and set its maximum concurrent operation count to 1. Then create an NSOperation subclass that performs the necessary steps to insert data into the database. Each chunk of data will correspond to a separate operation that will be added to the queue. Each operation will be performed in series until all are complete.
Here is an outline for the solution:
// Create a new queue to hold network operations.
self.operationQueue = [[NSOperationQueue alloc] init];
self.operationQueue.maxConcurrentOperationCount = 1;
// Split the large array into chunks of 20 items each.
NSInteger chunkSize = 20;
NSInteger i = 0;
NSInteger total = [lowMArray count];
while (i < total) {
NSInteger j = i;
NSMutableArray *chunk = [NSMutableArray alloc] init];
while (j < i + chunkSize - 1 && j < total) {
[chunk addObject:lowMArray[j]];
j++;
}
MyOperation *myOperation = [[MyOperation alloc] initWithArray:chunk];
self.operationQueue.addOperation(myOperation)
i += chunkSize;
}
MyOperation.h:
#interface MyOperation : NSOperation
- (instancetype)initWithArray:(NSArray *)chunk;
#property NSArray *chunk;
#end
MyOperation.m:
#implementation MyOperation
- (instancetype)initWithArray:(NSArray *)chunk
{
if (self = [super init]) {
self.chunk = chunk;
}
return self;
}
- (void)main
{
// Create Json data from lowMArray
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:self.chunk
options:NSJSONWritingPrettyPrinted
error:nil];
// Construct post request
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:[NSString stringWithFormat:#"%#/lows", _silServerBaseUrl]]];
request = [self applyAuth:request];
[request setHTTPMethod:#"POST"];
[request setValue:#"application/json; charset=UTF-8" forHTTPHeaderField:#"Content-Type"];
[request setHTTPBody:jsonData];
// Send post request
AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
NSURLSessionDataTask *dataTask = [manager dataTaskWithRequest:request completionHandler:^(NSURLResponse *response, id responseObject, NSError *error) {
if (error) {
// NSLog(#"Response Failed!");
} else {
// NSLog(#"Response Success!");
}
}];
[dataTask resume]; // runs task
}
#end
AFNetworking has support for its own NSOperation subclass in AFHTTPRequestOperation. An example can be found here. Also, the AFNetworking GitHub repository has an example for batch operations.
Based on your revised question, setting the completion block of each AFHTTPRequestOperation to handle the response and error can help to debug the problem.
Here is how it is done:
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation * _Nonnull operation, id _Nonnull responseObject) {
NSString* decodedResponse = [[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding];
NSLog(#"response %#", decodedResponse);
} failure:^(AFHTTPRequestOperation * _Nonnull operation, NSError * _Nonnull error) {
NSLog(#"error %#", error);
}];
It would be inserted after AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];.