Consistency in an Unpredictable World - Swift Language User Group

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Consistency in an Unpredictable World

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Hi, I’m Wendy! @wendyluwho

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Emoji & Deep Learning !

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4 -> 3 dozen developers

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Not all users are on the best phones, or best network Speed is important

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Network Usage (Optimizing data sent over API) App Startup Time Concurrency

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AVPlayer.resetAVAudioSessionCategoryToDefault() FBSDKSettings.configureForUseForApplication(application, withLaunchOptions:launchOptions) GSDAppIndexing.sharedInstance().registerApp(kAppStoreID) iRate.configureForUse() Adjust.appDidLaunch(adjustConfig) Stripe.configureForUse() DDLog.addLogger(DDTTYLogger.sharedInstance()) let fileLogger = DDFileLogger() fileLogger.logFileManager.maximumNumberOfLogFiles = 3 DDLog.addLogger(fileLogger) PIDeadlockDetector.enable() PICrash.sharedInstance().configureForUse() PINRemoteImageManager.configureForUse() CBLExperienceManager.configureForUse() NSValueTransformer.setValueTransformer(PIDateValueTransformer(), forName:kPINModelDateValueTransformerKey) CBLDeepLinkManager.sharedManager().configureServicesWithLaunchOp tions(launchOptions)

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Moved startup tasks to low-priority concurrent queue Reduced startup time by 50%

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AsyncDisplayKit

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Model Layer Immutable

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VC 1 VC 1 Pin Pin VC 2 ?!

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Wendy Users Kanye Taylor blockUser(users[1]) #

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A VC 2 Pin VC 1

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Updating Models

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Updating = Creating a new model

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Creating from JSON Dictionary

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let pin = Pin(dictionary:pinJSON) { "board" = { "created_at" = "Tue, 13 Aug 2013 16:38:36 +0000"; "id" = 418131215342691718; "name" = "spaces"; }; "comment_count" = 0; "description" = "At the top of my wish list for this fall is a giant chunky knit wool blanket."; "id" = "AVpd31ttshLHlWbcG9g_Kt3uVzZHjfHNvzwT20p6YnO6qzvQnqs_Z5A"; "image_square_url" = "https://s-media-cache-ak0.pinimg.com/b58cc94084407a39d62c83885ce4699e.jpg"; } Pin JSON

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Creating from Builder Object

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• imageURL = “https://www.123.com” Pin (Immutable) PinBuilder (Mutable) • title = “The best pin in the world” • board = “Cute Cats” • imageURL = “https://www.123.com” • title = • board = “Cute Cats” “The best pin in the world” “Meow”

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let pin = Pin(builder:pinBuilder)

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Loading and Caching

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“There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors.”

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image_url description user

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recipe

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PINCache

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Cache "id": "123" Pin123 "id" = "123" "image_url" : "http://new-url.com" "recipe" : {"ingredients": ["bananas"]} "imageURL" = "http://old-url.com" "board" = "Cakery" "id" = "123" "image_url" : "http://new-url.com" “board" = "Cakery" "recipe" : {"ingredients": ["bananas"]} Pin JSON

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Merge after initialization

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Observing for Changes

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Previously: KVO Notifications

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notificationManager.addObserverForUpdatedModel(user, block:{ (NSNotification) in // Update profile view here! })

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NSNotificationCenter.defaultCenter().addObserverForName("name", object: nil, queue: nil) { note in // ... } public func addObserverForName(name: String?, object obj: AnyObject?, queue: NSOperationQueue?, usingBlock block: (NSNotification) -> Void) -> NSObjectProtocol (__NSObserver)

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NSNotificationCenter.defaultCenter().removeObserver(self) NSNotificationCenter.defaultCenter().removeObserver(observer)

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notificationManager.addObserverForUpdatedModel(user, block:{ (NSNotification) in // Update profile view here! })

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class NotificationManager: NSObject { private var observerTokens: [String: AnyObject] = [:] deinit { unregisterAll() } func unregisterAll() { for token in observerTokens.values { NSNotificationCenter.defaultCenter().removeObserver(token) } } } http://moreindirection.blogspot.com/2014/08/nsnotiﬁcationcenter-swift-and-blocks.html

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notificationManager.addObserverForUpdatedModel(user, block:{ (NSNotification) in // Update profile view here! })

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let newUser = PIUser(builder:builder) NotificationManager.postModelUpdatedNotificationWithObject(newUser)

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Cache postModelUpdatedNotificationWithObject(newUser) “id” = “User123” “name” = “Taylor Swift”

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Making UI Updates

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notificationManager.addObserverForUpdatedModel(user, block: { [weak self] notification in if let user = notification.object as? PIUser { self?.user = user // Update profile view here! self?.titleLabel.text = user.name self?.imageView.setImageWithURL(user.imageURL) } })

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Consistency in an Unpredictable World

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https://engineering.pinterest.com/blog/immutable-models- and-data-consistency-our-ios-app Additional Resources https://code.facebook.com/posts/340384146140520/ making-news-feed-nearly-50-faster-on-ios/ https://github.com/linkedin/RocketData