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Delighting your users with SBJson 4 Stig Brautaset @stigbra ~ github.com/stig

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What’s more important to you? Time until your users see the last record? Or until they see the first? ! Do you cut page size to reduce the wait?

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Download-then-parse Time to first record Time to last record

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Chunked delivery Time to first record Time to last record

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Multi-core chunked delivery Time to first record Time to last record

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Relative time to first record 0 250 500 750 1000 1 record 10 records 100 records 1000 records Chunked delivery Download-then-parse

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NSJSONSerialisation • Supports NSStream! • But can’t do chunked delivery. • We can do better!

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SBJson • Chunked delivery since version 3 (in June 2011) • But it was confusing and cumbersome to use… • …with multiple delegates required

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SBJson 4 • Focus on chunked delivery • Introduces a block-based interface • Drops category & OO interfaces

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Multi-root JSON id parser = [SBJson4Parser multiRootParserWithBlock:block errorHandler:eh]; ! ! [parser parse:data("[]{")]; // calls block(@[]) ! [parser parse:data("}[]"]; // next part of stream // calls block(@{}) // calls block(@[])

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Multi-root JSON id parser = [SBJson4Parser multiRootParserWithBlock:block errorHandler:eh]; ! ! [parser parse:data("[]{")]; // calls block(@[]) ! [parser parse:data("}[]"]; // next part of stream // calls block(@{}) // calls block(@[])

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Use with custom
 NSURLSessionDataDelegate - (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dt didReceiveData:(NSData *)data { ! switch ([parser parse: data]) { // handle various returns here… } }

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–Me, early 2011 “But what if I am consuming a 3rd-party API and they just give me a long list?”

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Unwrap the root array! id parser = [SBJson4Parser unwrapRootArrayParserWithBlock:block errorHandler:eh]; ! [parser parse:data("[[],{")]; // calls block(@[]) ! [parser parse:data("},true]")]; // calls block(@{}) // calls block(@(YES))

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Unwrap the root array! id parser = [SBJson4Parser unwrapRootArrayParserWithBlock:block errorHandler:eh]; ! [parser parse:data("[[],{")]; // calls block(@[]) ! [parser parse:data("},true]")]; // calls block(@{}) // calls block(@(YES))

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Unwrapping is for root-level arrays only!

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Compromise: Corrupted / incomplete JSON [ {}, [], ***###$#”>P ! ! ! block(@{}) block(@[]) errorHandler(…)

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SBJson’s Blocks SBJson4ValueBlock block = ^(id obj, BOOL *stop) { if (some_condition) { *stop = YES; } else { // do something with obj } }; ! ! SBJson4ErrorBlock eh = ^(NSError *err) { NSLog(@"OOPS: %@", err); };

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SBJson4ParserStatus switch ([parser parse:data]) { case SBJson4ParserStopped: case SBJson4ParserComplete: NSLog(“Done!"); case SBJson4ParserWaitingForData: break; case SBJson4ParserError: NSLog(@"Ouch, I'm hurt!"); break; }

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Two CocoaPods! To allow both version 3 and 4 in the same application.