Production Swift - Speaker Deck

Production Swift

by Ash Furrow

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Production Swift Ash Furrow

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Objective-C

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Agenda 1. Swift is Awesome 2. Tools are Immature 3. Be Informed

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Swift is Different

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How is it different? • Static vs. Dynamic • Prefers immutability • Encourages functional programming • Safe (well, safer) • Experimentation via Playgrounds

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Optional Protocol Methods @protocol MyProtocol @required - (void)doSomethingNecessary; @optional - (void)doSomethingOptional; @end

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Optional Protocol Methods protocol MyProtocol { func doSomethingNecessary() optional func doSomethingOptional() } // Compiler Error!

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Optional Protocol Methods func doSomethingNecessary() optional func doSomethingOptional() } @objc protocol MyProtocol {

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Objective-C Interoperability • Interoperability comes at the cost of Swift’s purity • We loose a lot of safety • Don’t just add @objc because it’ll make code compile

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Swift is Better

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Objective-C Hurts Me if (indexPath.section == 0) { if (indexPath.row == 0) { } else if (indexPath.row == 1) {   } else if ... } else if (indexPath.section == 1) { if (indexPath.row == 0) { } else if (indexPath.row == 1) {   } else if ... } else if ...

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Pattern Matching switch (indexPath.section, indexPath.row) { case (0, 0): case (0, 1): case (1, 0): case (1, 1): default: // nop }

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Pattern Matching case (let section, 0) where section % 2 == 0: case (0, let row): case let (0, row) where validate(row):

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Self-Evaluating Lazy Closures class MySweetViewController: UIViewController { lazy var button: UIButton = { let button = UIButton.buttonWithType(.System) // configure button return button }() }

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And many more … enums closures tuples generics compile-time awesomeness saved a kitten from a fire went to highschool prom with me function currying functions are closures array.sort(<) better terroir immutability by default type inference discovered penicillin operator overloading clear mutability syntax native collections REPL multiple return types concise pattern-matching

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Tools are Immature

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Apple Tools • Xcode, clang, Playgrounds, SourceKit, code signing, frameworks … • All are unstable • Causes frustrations • Causes delays • Causes hair loss

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github.com/artsy/eidolon

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Open Source by Default

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Using Swift doubled our development time

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“We don’t expect to make our deadline.”

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Eidolon Problems • Enterprise code signing issues with Xcode 6.1 • Compiler segfaults with optimizations enabled • Constant Xcode/SourceKit crashes • Unit testing problems

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Burnout

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We made our deadline

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Eidolon Awesomeness • We helped pioneer a new way of writing iOS software • Created many new libraries, tools, and resources • Used others’ new tools and contributed bug reports and fixes • Learnt a tonne, shared with others

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Apple Tools • Someday soon, these will be ready for everyday use • But not today • You will have unanticipated problems • There will be no known solutions or workarounds • Until then, use with caution

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3rd Party Tools • CocoaPods 0.36 has support for Swift • Tremendous amount of open source effort • Pre-1.0, use with caution • Carthage is new but promising • Pre-1.0, use with caution

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Be Informed

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Making a Choice • What’s your aversion to risks? • How hard is your deadline? • Why are you building something? • How open is your team to learning a new language?

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Why Bother?

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Swifxpert Become a

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Blog

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Risks Rewards vs.

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Be Aware • Don’t be afraid to revisit your decision • It’s OK to switch back to Objective-C