A short presentation we held at the Stockholm CocoaHeads meeting March 5th 2012 on concurrent networking in iOS.

1. CONCURRENT NETWORKING
– MADE EASY!
CocoaHeads Stockholm, March 5 2012
MARTHIN FREIJ / AMAZING APPLICATIONS

3. AMAZING APPLICATIONS / IN SHORT
A two-man army of digital production
veterans, on a crusade to delight people
with pixel perfect design, delicate code
and stunning user experiences.
We work hard to ensure that everything
from concept and user interaction design
to animations and technical
implementation is as sleek as possible.

4. MARTHIN FREIJ / SENIOR DEVELOPER JIMMY POOPUU / ART DIRECTOR
Has written million lines of code as a A tech savvy pixel pusher and design geek
software developer and held countless with over 15 years of experience working
lectures as technical trainer during the with global brands in digital channels.
past 10 years for clients in the bank, Also a confused father and a avid gamer.
finance and media sector.
CLIENT SHORT LIST:
CLIENT SHORT LIST: Vin & Sprit (Absolut Vodka & Malibu Rum), IKEA,
ICA Banken, Handelsbanken, Bonnier, Dagens Scania, Electrolux, Nokia, SCA (Libresse)
Nyheter, Dagens Industri

5. NJUICE WKLY GREEN KITCHEN

6. CONCURRENT NETWORKING
– MADE EASY!
CocoaHeads Stockholm, March 5 2012
MARTHIN FREIJ / AMAZING APPLICATIONS

7. MADE EASY?
IS IT HARD
IN THE FIRST PLACE?

8. APPLE PROVIDE SIMPLE
API’S FOR NETWORKING

9. NSURLConnection
NSURLRequest
NSURLResponse

10. ;(
FEW DEVELOPERS USE THEM

11. 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;

12. AND MAYBE YOU WANT TO DO
MORE THAN ONE REQUEST
AT THE TIME?

13. THEN YOU NEED TO
KEEP TRACK
OF YOUR REQUESTS
AND CONNECTIONS

14. WE TEND TO USE BOILERPLATE CODE
WRITTEN BY SOMEONE ELSE

15. LIKE NETWORK LIBRARIES

16. ASIHTTPREQUEST

17. DOH! DISCONTINUED!

18. AFNETWORKING

19. !
BUGS!
RACE CONDITIONS!
MEMORY LEAKS!

20. IT TURNS OUT
TO BE KIND OF HARD

21. NEW STUFF IN iOS 5

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

23. ☞ NSURLRequest
☞ NSOperationQueue
☞ Completion Handler

24. // Create the request
NSURL *url = [NSURL URLWithString:@"https://the.api.com/method/"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
// Create the queue
NSOperationQueue *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
});
}];

25. ONE MORE THING...

26. CORE DATA AND CONCURRENCY HAVEN’T
ALWAYS BEEN BEST BUDDIES

27. UNTIL NOW IN iOS 5

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

29. IMPORT DATA EXAMPLE (1 / 2)
☞ Set your main context to execute on Main Queue
(NSMainQueueConcurrencyType)
☞ 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

30. IMPORT DATA EXAMPLE (2 / 2)
☞ On the import context, call performBlock and do the import (i.e.
download data, validate it, import it, purge old data etc)
☞ 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)

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

32. 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];
}];
}];

33. THATS IT, THANKS FOR YOUR TIME!
www.amazing-apps.se