Swift LA22 June 2015

eHarmony

• Introduction• What You Might Have Missed at WWDC• Swift 2.0• Swift & Enterprise & eHarmony• Questions?

Agenda

“We came together in 2000 believing that with a mix of psychology and some cutting edge technology, we could create relationships that were happier, more fulfilling and enduring.With over 61 million registered users, we’ve successfully married more than 565,000 couples, and are responsible for nearly 5% of marriages in the US — that’s 438 people every day that say ‘I Do’ because of eHarmony.”

“Millions of people have used eHarmony’s Compatibility Matching System to find compatible long-term relationships. Today, an average of 438 eHarmony members marry every day in the United States as a result of being matched on the site.”

Who is eHarmony?

Currently, we maintain Desktop Web, Mobile Web, iOS and Android apps for our scientific matching service.

Our iOS App currently boasts:• 8 billion downloads• Best selling app• Biggest grossing app

The team has been busy!

The eHarmony App

• Dr. Gary Philipp – Sr. Manager, Mobile EngineeringGary has a PhD in Engineering and a Masters in Behavioral Science. He is the old

man of the group (programming Apple products for over 30 years) and his first computer was an Apple II.

• Chris Truman – iOS EngineerSelf taught iOS developer, born and raised in LA. Previously worked at Urbanspoon

and TripAdvisor. Currently mentoring students in Swift through the Thinkful & One Month Swift programs. Loves Dogs, Comic Books, and long walks on the beach.

• Premal Mistry – iOS EngineerPremal loves designing and developing apps for iOS and Android and has over 6

years of experience in Software Development. He has a Masters in Computer Science and is passionate about learning new technologies (Swift, Design Patterns, Animation, etc). During weekends, I love to watch movies, TV shows, hanging out with friends and Yelping various food places in LA.

• Heena Rastogi – Senior iOS EngineerHeena earned a Masters in Computer Science (Multimedia and Creative

Technologies) and has been developing iOS apps for the past 6 years. She loves being a part of development projects that are focused on creative and exciting technologies. Outside of coding, she enjoys reading, running on the beach and listening to electronic music.

The Team

• UIStackView• Rich Playgrounds• Slide Over & Split View & PiP Video• Universal Links• App Search & CoreSpotlight• SFSafariViewController• App Transport Security• App Thinning• Storyboard References• UI Testing• Metal & Games• TestFlight and Push Notifications

What You Might Have Missed at WWDC 2015

• Axis• Distribution• Spacing• Animatable

UIStackView

• Markdown• Multi-Pages• Embedded Resources

Rich Playgrounds

• Launch Screen Storyboard• Autolayout & Size Classes• Window vs Screen

Slide Over & Split View & PiP

• App Site Association• Similar to Android Default Intents

Universal Links

• Background Indexing• NSUserActivity• Web Markup• Meta Data

App Search & CoreSpotlight

• Separate process• Cookies & Keychain• Tint Color• Custom Activity Items

SFSafariViewController

• HTTPS is mandatory-ish• Info.plist disabling• Exception Domains

App Transport Security

• Asset Splitting - @1x, @2x, @3x• On Demand Resources• BitCode

App Thinning

• Split up Large Storyboards• Custom Unwind Segues

Storyboard References

• New Testing Bundle Type• Record a Script

UI Testing

• Core Animation• On the Mac• ReplayKit, GameplayKit, ModelKit

Metal & Games

• Tester Limit increased to 2000• Push Notifications Text Input• 4k Push Payload Limit Increase• Feedback Service will be deprecated in

2016

TestFlight & Push Notifications

• Checking API Availability• Synthesized Headers• Protocol Extension• Error Handling• And more…

What’s New in Swift 2.0

Apple always rolls out new API’s and classes throughout the year.

How do we check for API & Class availability?

Checking API Availability in Swift

The old way:if NSClassFromString("SFSafariViewControler") != nil { let eHAdviceVC = SFSafariViewController(URL: url, entersReaderIfAvailable: true) eHAdviceVC.delegate = self presentViewController(eHAdviceVC, animated: true, completion: nil) } else { let eHAdviceVC = eHAdviceViewController(URL: url); presentViewController(eHAdviceVC, animated: true, completion: nil)}

Checking API Availability in Swift

Checking API Availability in Swift

The new way:if #available(iOS 9, OS X 10.10, watchOS 2, *) {

let eHAdviceVC = SFSafariViewController(URL: url, entersReaderIfAvailable: true) eHAdviceVC.delegate = self presentViewController(eHAdviceVC, animated: true, completion: nil) } else { let eHAdviceVC = eHAdviceViewController(); presentViewController(eHAdviceVC, animated: true, completion: nil)}

Synthesized header files:

Xcode 7 scans through your code and produces virtual header files that summarize the exposed methods with none of the code

Documentation - Similar to Apple's own classes

How to generate synthesized headers in Xcode 7?Xcode 7, go to Navigate > Generated Interface.

Synthesized Headers

Synthesized Headersextension NSURLRequest: URLRequestConvertible { public var URLRequest: NSURLRequest}

func URLRequest(method: Method, URL: URLStringConvertible) -> NSURLRequest

/** Creates a request using the shared manager instance for the specified method, URL string, parameters, and parameter encoding.

:param: method The HTTP method. :param: URLString The URL string. :param: parameters The parameters. `nil` by default. :param: encoding The parameter encoding. `.URL` by default.

:returns: The created request.*/public func request(method: Method, URLString: URLStringConvertible, parameters: [String: AnyObject]? = nil, encoding: ParameterEncoding = .URL) -> Request

/** Creates a request using the shared manager instance for the specified URL request.

If `startRequestsImmediately` is `true`, the request will have `resume()` called before being returned.

:param: URLRequest The URL request

:returns: The created request.*

Protocol Extensions

Protocols can be extended to provide method and property implementations to conforming types.

You can use protocol extensions to provide a default implementation to any method or property requirement of that protocol.

Protocol ExtensionsExample:

let ageOfEmployees: [Int?] = [30, 32, nil, 45, 50, 12, 8, 25, nil]

extension SequenceType where Generator.Element: OptionalType { var purify: [Self.Generator.Element.T] { return self.map { $0.optional }.filter { $0 != nil }.map { $0! } }}

let ageOfEmployees: [Int?] = [30, 32, nil, 45, 50, 12, 8, 25, nil]ageOfEmployees.purify

[30, 32, 45, 50, 12, 8, 25]

Error Handling

Example:func refreshActivityFeed() { let refreshToken = login() loadActivityFeed(refreshToken) updateUI()}

Error HandlingThe Old Way:func refreshActivityFeed() { let refreshToken:String? = login(username, error:&error) if (error != nil) { if let error = error { switch (error.code) { case ERROR_UNAUTHORIZED: showLoginVC() case ERROR_FORBIDDEN: showErrorAlert() case ERROR_NOT_FOUND: showLoginVC() default: showErrorAlert() } } } else { // Fetch the most recent activity feeds from the server // Parse and prepare data structure // Update UI loadActivityFeed(refreshToken!) updateUI() }}

The New Way:func refreshActivityFeed() { do { let refreshToken = try login(username) loadActivityFeed(refreshToken) updateUI() } catch (LoginError.ERROR_UNAUTHORIZED) { showLoginVC() } catch (LoginError.ERROR_FORBIDDEN) { showErrorAlert() } catch (LoginError.ERROR_NOT_FOUND) { showLoginVC() } catch { showErrorAlert() }}

Error Handling

Error HandlingRepresenting Errors

• ErrorType is a protocol in the Swift Standard Library

• Any type that conforms to ErrorType can be thrown and caught

• Can make your own types conform as well

• enum is great for groups of related errors

enum LoginError : ErrorType { case ERROR_UNAUTHORIZED case ERROR_FORBIDDEN case ERROR_NOT_FOUND case ERROR_NOT_ALLOWED case ErrorWithMessage(code: Int, message: String)}

Throwing Errors:enum VendingMachineError: ErrorType { case InvalidSelection case InsufficientFunds(required: Double) case OutOfStock}

func purchaseItemFromVendingMachine(item: VendingItem) throws -> Bool { if item.count() > 0 { // ..... return true } else { throw VendingMachineError.OutOfStock }}

Error Handling

Catching and Handling Errors:func refreshActivityFeed() { do { let refreshToken = try loginWithUserName(username) loadActivityFeed(refreshToken) updateUI() } catch (LoginError.ERROR_UNAUTHORIZED) { showLoginVC() } catch (LoginError.ERROR_FORBIDDEN) { showErrorAlert() } catch (LoginError.ERROR_NOT_FOUND) { showLoginVC() } catch { showErrorAlert() }}

Error Handling

Disabling Error Propagation:

try! loadConfiguration()

Error Handling

Specifying Cleanup Actions:func processFile(filename: String) throws { if exists(filename) {

do { let file = try open(filename) defer { close(file) }

while let line = try file.readline() { ... }

} catch {...

} }}

Error Handling

And More…Guard:func validateJSON() -> Bool { guard let name = person["name"] else { return false } ..... ..... return true}

• Designed to solve pyramid of doom problem• Extremely useful for early exit

Swift & Enterprise & eHarmony

• Why?• Bridging & Migration• eHarmony’s Plan to Tackle

• Simpler to read

• Type safety and hence code safety

• Interacts with Objective-C Runtime seamlessly

• Take advantage of Objective-C APIs and Cocoa design patterns

• Open Source - we gain flexibility and freedom

• Other platforms can also adopt Swift

Why?

3 important aspects of Swift / Objective-C compatibility:

• InteroperabilityAbility to interface between Swift and Objective-C in either direction

• Mix and MatchAllows you to create mixed-language apps containing both Swift and Objective-C files that can communicate with each other

• MigrationMigration from existing Objective-C code to Swift is made easy with interoperability and mix and match, making it possible to replace parts of your Objective-C apps with the latest Swift features

Bridging & Migration

3 New features introduced for Objective-C :

• Nullability for Objective-C

• Lightweight Generics

• Kind of

Bridging & Migration

Bridging & Migration

Objective-C

@interface SNGFeedView@property(nonatomic, readonly) UIView *photoView;@property(nonatomic, readonly, copy) NSArray *feedViews;- (UIView*) photoViewForFeed:(SSFeed) photoFeed;@end

Swift

class SNGFeedView { var photoView : UIView? var feedViews: [AnyObject]! func photoView(photoFeed:SSFeed) - > UIView}

Indicate whether Objective-C/C pointers can be nil

• Better communicate intent of APIs

• Allows improved static checking

• Improves usability of APIs in Swift

Nullability

Nullability Qualifiers

Nullability

Qualifier Usage Swift

nullable Pointer may be nil UIView?

nonnull nil is not a meaningful value

UIView

null_unspecified Neither nullable nor nonnull applies

UIView!

NOTE: Compiler does not change the way it generates code because of a non-null annotation.

Example:

NS_ASSUME_NONNULL_BEGIN

@interface SNGFeedView@property(nonatomic,readonly,nullable) UIView *photoView;@property(nonatomic, readonly,copy) NSArray *feedViews;-(UIView*) photoViewForFeed:(SSFeed) photoFeed;@end

NS_ASSUME_NONNULL_END 

Audited regions make default assumptions about some pointers:• Single-level pointers are assumed to be nonnull• NSError** parameters are assumed to be nullable for

both levels• Only annotate the nullable or null_unspecified cases 

Nullability

Allow collections to be parameterized by element type:

“An array of views” , “A dictionary mapping strings to images”

• Improve expressivity of APIs

• Make collections easier to use

• Enable better static type checking

Lightweight Generics

Objective–C@interface SNGFeedView@property(nonatomic)NSArray <UIView*> feedSubviews;@property(nonatomic,assign)BOOL filter;@end

Swiftclass SNGFeedView {var subviews: [UIView] { get }}

Lightweight Generics

• It tells compiler it’s object of some kind of of given type

extern __kindof NSApplication *NSApp; // NSApplication instanceNSObject *object = NSApp; // convert to super classMyApplication *myApp = NSApp; // implicit downcast subclassNSString *string = NSApp // Incorrect

• Much more useful than id, more type information in API contract

• Allows messaging subclass methods[NSApp praiseUser] // Invokes MyApplication method

KindOf Types

• Modernization of Objective-C

• Generating Bridging Headers

• Incremental Migration

eHarmony’s Plan to Tackle

Before you start:

• Create a Swift class for your corresponding Objective-C .m and .h

• Import relevant system frameworks

• Fill out an Objective-C bridging header if you need to access Objective-C code from the same app target in your Swift file

• To make your Swift class accessible and usable back in Objective-C, make it a descendant of an Objective-C class or mark it with the @objc attribute

Migration

As you work:

• Set up your Swift class by subclassing Objective-C classes, adopting Objective-C protocols, and more.

• See “Adopting Cocoa Design Patterns” for information on translating common design patterns.

• To translate your properties from Objective-C to Swift, read Properties in “The Swift Programming Language.”

• Declare simple macros as global constants, and translate complex macros into functions.

Migration

After you finish:

• Update import statements in your Objective-C code (to #import "ProductModuleName-Swift.h"), as described in “Importing Code from Within the Same App Target”

• Remove the original Objective-C .m file from the target by deselecting the target membership checkbox

• Update your code to use the Swift class name instead of the Objective-C name if you gave the Swift class a different name

Migration

Questions?