iAsync Functional Programming in Objective-C

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1. iAsync Functional Programming in Objective-C Alexander Dodatko 2013
4. Over 900,000 apps (as of June 2013)
7. NSData* jsonData = nil; jsonData = [ NSData dataWithContentsOfURL: RESOURSE ];
10. Asynchronous Programming
11. @protocol NSURLConnectionDataDelegate <NSURLConnectionDelegate> @optional - (void)connection: didReceiveResponse: - (void)connection: didReceiveData: - (void)connectionDidFinishLoading: - (void)connection: didFailWithError: @end
12. Too Much Code
13. Objectice-C Blocks
14. NS_AVAILABLE(10_7, 5_0); + (void)sendAsynchronousRequest: queue: completionHandler:
15. void (^HANDLER_BLOCK)( NSURLResponse* response, NSData* data, NSError* connectionError)
17. Progress Cancel
19. NSURL *url = [NSURL URLWithString:@"https://...."]; NSURLRequest *request = [NSURLRequest requestWithURL:url]; id onSuccess = ^(NSURLRequest *, NSHTTPURLResponse *, id JSON) { NSLog( @"App.net Global Stream: %@", JSON ); }; AFJSONRequestOperation *operation = [ AFJSONRequestOperation JSONRequestOperationWithRequest: request success: onSuccess failure: nil ]; [ operation start ];
20. Dependencies
21. When using methods which return blocks they can be very convenient. However, when you have to string a few of them together it gets messy really quickly
22. [remoteAPIWithURL:url1 success:^(int status){ [remoteAPIWithURL:url2 success:^(int status){ [remoteAPIWithURL:url3 success:^(int status){ [remoteAPIWithURL:url2 success:^(int status){ //success!!! }]; }]; }]; }];
23. It was not uncommon when using AFNetworking in Gowalla to have calls chained together in success blocks. My advice would be to factor the network requests and serializations as best you can into class methods in your model. Then, for requests that need to make sub-requets, you can call those methods in the success block.
24. Callback Hell
26. AFURLConnectionOperation
27. Working with independent data sets in parallel and then combining them into a final result is non-trivial in Cocoa, and often involves a lot of synchronization
28. __block NSArray *databaseObjects, fileContents; NSOperationQueue *backgroundQueue = [[NSOperationQueue alloc] init]; NSBlockOperation *databaseOperation = [NSBlockOperation blockOperationWithBlock:^{ databaseObjects = [databaseClient fetchObjectsMatchingPredicate:predicate]; }]; NSBlockOperation *filesOperation = [NSBlockOperation blockOperationWithBlock:^{ NSMutableArray *filesInProgress = [NSMutableArray array]; for (NSString *path in files) { [filesInProgress addObject:[NSData dataWithContentsOfFile:path]]; } fileContents = [filesInProgress copy]; }]; NSBlockOperation *finishOperation = [NSBlockOperation blockOperationWithBlock:^{ [self finishProcessingDatabaseObjects:databaseObjects fileContents:fileContents]; NSLog(@"Done processing"); }]; [finishOperation addDependency:databaseOperation]; [finishOperation addDependency:filesOperation]; [backgroundQueue addOperation:databaseOperation]; [backgroundQueue addOperation:filesOperation]; [backgroundQueue addOperation:finishOperation];
29. Rather than using mutable variables which are replaced and modified in-place, RAC provides signals (represented by RACSignal) that capture present and future values.
30. When Design Patterns are NOT enough
31. Meet the Async Operation CancelBlock (^AsyncOperation) ( ProgressCallback, CancelCallback, CompletionCallback ) {...};
32. Sequence JFFAsyncOperation sequence = sequenceOfAsyncOperations( @[ op1, op2, opN ] );
33. Sequence of Attempts JFFAsyncOperation sequence = trySequenceOfAsyncOperations( @[ op1, op2, opN ] );
34. Parallel execution JFFAsyncOperation sequence = groupOfAsyncOperations( @[ op1, op2, opN ] ); CompletionCallback
35. Waterfall JFFAsyncOperation sequence = bindSequenceOfAsyncOperations( op1, @[ b1, b2, bN ] );
36. Function = Command + Composite
37. Any Complexity Tasks
38. loadFromNet = sequenceOfAsyncOperations( @[ login, loadFromNet ] ); loadRawData = trySequenceOfAsyncOperations( @[ loadFromFSCache, loadFromNet ] ); JFFAsyncOperation getData = bindSequenceOfAsyncOperations( loadRawData, @[ parseBinder, filterBinder ] );
39. iAsync bit.ly/1bLdN59
40. Does anyone use it?
41. Wishdates
42. Sitecore
43. Pitfalls Large codebase No PodSpec No Documentation No Community No Versioning policy
45. Vladimir Gorbenko Gorbenko.Vova@gmail.com Vova.Gorbenko.mac github.com/volodg iAsync Author
46. Oleksandr Dodatko dodikk88.tutor@gmail.com alexander.dodatko.work @dodikk88 github.com/dodikk