concurrent networking - made easy

CONCURRENT NETWORKING – MADE EASY!

CocoaHeads Stockholm, March 5 2012MARTHIN FREIJ / AMAZING APPLICATIONS

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AMAZING APPLICATIONS / IN SHORT

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MARTHIN FREIJ / SENIOR DEVELOPER

WKLY GREEN KITCHENNJUICE

CONCURRENT NETWORKING – MADE EASY!

CocoaHeads Stockholm, March 5 2012MARTHIN FREIJ / AMAZING APPLICATIONS

MADE EASY?IS IT HARD IN THE FIRST PLACE?

APPLE PROVIDE SIMPLE API’S FOR NETWORKING

NSURLConnectionNSURLRequestNSURLResponse

FEW DEVELOPERS USE THEM

;(

BECAUSE THEY REQUIRE A LOT OF BOILERPLATE CODE

- (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate;

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response;- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data;- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error;- (void)connectionDidFinishLoading:(NSURLConnection *)connection;

AND MAYBE YOU WANT TO DO MORE THAN ONE REQUEST

AT THE TIME?

THEN YOU NEED TO KEEP TRACK

OF YOUR REQUESTS AND CONNECTIONS

WE TEND TO USE BOILERPLATE CODE WRITTEN BY SOMEONE ELSE

LIKE NETWORK LIBRARIES

ASIHTTPREQUEST

DOH! DISCONTINUED!

AFNETWORKING

BUGS!RACE CONDITIONS!MEMORY LEAKS!

!

IT TURNS OUT TO BE KIND OF HARD

NEW STUFF IN iOS 5

+ (void)sendAsynchronousRequest:(NSURLRequest *)request queue:(NSOperationQueue*) queue completionHandler:(void (^)(NSURLResponse*, NSData*, NSError*)) handler;

NSURLRequestNSOperationQueueCompletion Handler

☞☞☞

// Create the requestNSURL *url = [NSURL URLWithString:@"https://the.api.com/method/"];NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];

// Create the queueNSOperationQueue *queue = [[NSOperationQueue alloc] init];queue.name = @"com.your.unique.queue.name";

[NSURLConnection sendAsynchronousRequest:request queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) { // If there was an error getting the data if (error) { dispatch_async(dispatch_get_main_queue(), ^(void) { // Display error message in UI }); return; } // Do stuff with the data dispatch_async(dispatch_get_main_queue(), ^(void) { // Update UI });}];

ONE MORE THING...

CORE DATA AND CONCURRENCY HAVEN’T ALWAYS BEEN BEST BUDDIES

UNTIL NOW IN iOS 5

- (id)initWithConcurrencyType:(NSManagedObjectContextConcurrencyType)ct;- (void)setParentContext:(NSManagedObjectContext*)parent;- (void)performBlock:(void (^)())block;

NSManagedObjectContext

Set your main context to execute on Main Queue(NSMainQueueConcurrencyType)

☞IMPORT DATA EXAMPLE (1 / 2)

Create an import context and tell Core Data to create a new queue for it (NSPrivateQueueConcurrencyType)

☞Set the main context as the import contexts parentContext☞

On the import context, call performBlock and do the import (i.e. download data, validate it, import it, purge old data etc)

☞IMPORT DATA EXAMPLE (2 / 2)

Save changes on the import context. This will stage it up one level (to the main context)

☞Save changes on the main context. This will persist it on the associated persistent store (and update NSFetchedResultControllers etc)

☞

// Setup the main context (probably in the AppDelegate)[[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];

NSManagedObjectContext *importContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];

importContext.parentContext = self.managedObjectContext;

[importContext performBlock:^{

// Download data, import etc..

NSError *importError = nil; [importContext save:&importError];

[importContext.parentContext performBlock:^{ NSError *parentError = nil; [importContext.parentContext save:&parentError]; }];}];

THATS IT, THANKS FOR YOUR TIME!

www.amazing-apps.se