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ReactiveCocoa Lessons Learned Rob Pearson @robpearson

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Maple Pixel Everyday Transit 1.0 coming soon ...

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FrieNDA

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Everyday ReactiveCocoa 1. Functional Programming Briefly 2. Signals and Pipelines 3. RAC Lessons Learned

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Functional Programming Briefly

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Signals and Pipelines

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Demo

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Transit Dashboard Pipeline Inputs: * List of Everyday Trips (Favourites) * GPS Location * Time Outputs: * Next Transit Trip

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Pipelines == RACSignals

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RACSignal Example [RACSignal createSignal:^(id

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So we have Pipelines/ Signals. Now what?

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Two Options RAC(self, viewModel.something) RACSignal subscribeNext: error: completed:

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RAC Lessons Learned

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KVO

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No, Seriously ... KVO!

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Key Value Observing // Bind Transit Trips to Table View [RACObserve(self.viewModel, everydayTransitTrips) subscribeNext:^(id x) { @strongify(self); [self.tableView reloadData]; }];

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Work with Protocols

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rac_signalForSelector [[self rac_signalForSelector:@selector(searchBar:textDidChange:) fromProtocol:@protocol(UISearchBarDelegate)] subscribeNext:^(RACTuple *value) { @strongify(self); UISearchBar *searchBar = value.first; if (searchBar == self.departingLocationsSearchBar) { [self.viewModel filterDepartingLocationsByName:self.departingLocationsSearchBar.text]; } else { [self.viewModel filterArrivingLocationsByName:self.arrivingLocationsSearchBar.text]; } }];

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Take advantage of RAC Category Methods

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NotificationCentre RACSignal *appActiveSignal = [[[[NSNotificationCenter.defaultCenter rac_addObserverForName:UIApplicationDidBecomeActiveNotification object:nil] mapReplace:@YES] startWith:@YES] setNameWithFormat:@"%@ appActive", self];

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Signal Tips and Tricks

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Reactive Timer 1 Map Time

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Reactive Timer 1 [[[[[RACSignal interval:60 onScheduler:[RACScheduler scheduler]] map:^id(NSDate *timestamp) { @strongify(self); if (self.hasEverydayTrips != nil && [@(YES) isEqualToNumber:self.hasEverydayTrips]) { return @"SEQ"; } else { return @"Everyday Transit"; } }] startWith:@"Everyday Transit"] distinctUntilChanged] deliverOn:[RACScheduler mainThreadScheduler]];

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Reactive Timer 2 Empty Signal with a delay.

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Reactive Timer 2 RACSignal *nextTransitTripIntervalSignal = [RACSignal interval:1 onScheduler:[RACScheduler scheduler]]; RACSignal *currentUserLocationRefreshDelay = [[RACSignal empty] delay:60]; RACSignal *currentUserLocationRefreshSignal = [[[self.locationService.locationSignal take:1] concat:currentUserLocationRefreshDelay] repeat];

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Real Power is combing and chaining signals

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Protips • Start by reading IntroToRx.com • Start small and iterate. • Logging w/ Something like Cocoalumberjack • Asks questions by opening issues at http://github.com/ ReactiveCocoa/

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Challenges • Thinking like a Functional Programmer • ReactiveCocoa Doco • Debugging

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References • Github Repo: http://github.com/ReactiveCocoa/ • Ray Wenderlich Tutorial: https://bit.ly/1rXA31Y • Big Nerd Ranch Tutorial: https://bit.ly/1mp04mI • FRP on iOS by Ash Furrow: https://leanpub.com/iosfrp • Brent Simmons on ReactiveCocoa: https://bit.ly/PcyjCL

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Questions?