Swift: Apple's New Programming Language for iOS and OS X

Swift Apple’s New Programming Language Sasha Goldshtein CTO, Sela Group blog.sashag.net @goldshtn Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Apple WWDC Announcements • iOS 8 and OS X Yosemite • Xcode 6 • Swift Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Minus Bazillion Points “Every feature starts out in the hole by 100 points, which means that it has to have a significant net positive effect on the overall package for it to make it into the language.” – Eric Gunnerson, C# compiler team If a language feature starts at -100 points, where does a new language start?! Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Objective-C Popularity • Objective-C owes all its popularity to the meteoric rise of the iPhone App Store introduced Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

What’s Wrong with Objective-C Exhibit One // Ignore the horrible syntax for a second. // But here's the charmer: // 1) if 'str' is null, we return NSNotFound (232-1) // 2) if 'arr' is null, we return 0 + (NSUInteger)indexOfString:(NSString *)str inArray:(NSArray *)arr { return [arr indexOfObject:str]; } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

What’s Wrong with Objective-C Exhibit Two // This compiles and crashes at runtime with: // "-[__NSArrayI addObject:]: unrecognized selector // sent to instance 0x7a3141c0" NSMutableArray *array = [NSArray array]; [array addObject:@"hello"]; Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

What’s Wrong with Objective-C Exhibit Three NSMutableArray *array = [NSMutableArray array]; [array addObject:@"hello"]; [array addObject:@17]; // This compiles just fine NSString *string = array[1]; // Yes, the "17" // This works and prints 17 NSLog(@"%@", string); // But this crashes NSLog(@"%@", [string stringByAppendingString:@"hmm"]); Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Swift Language Principles • Clean and modern • Type-safe and generic • Extensible • Functional • Productive • Compiled to native • Seamlessly interops with Objective-C Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Why Not an Existing Language? • Good philosophical question • If you want some more philosophy: http://s.sashag.net/why-swift We will now review some of the interesting language decisions, which make Swift different from mainstream languages Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Variables and Constants let size = 42 let name = "Dave" var address = "14 Franklin Way" address = "16 Calgary Drive" var city: String city = "London" var pi: Double = 3.14 Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Strings and Arrays var fullAddress = city + " " + address println("(name)'s at (city.capitalizedString)") var customers = ["Dave", "Kate", "Jack"] var addresses = [String]() addresses += fullAddress if customers[2].hasPrefix("Ja") { customers.removeAtIndex(2) } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Dictionaries var orderSummary = [ "Dave": 11000, "Kate": 14000, "Jack": 13500 ] orderSummary["Kate"] = 17500 for (customer, orders) in orderSummary { println("(customer) -> (orders)") } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Null “I call it my billion-dollar mistake. It was the invention of the null reference in 1965. […] I couldn't resist the temptation to put in a null reference, simply because it was so easy to implement. This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years.” – Sir Charles Antony Richard Hoare, 2009 Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Optional Types var myName: String myName = nil // Does not compile! var jeffsOrders: Int? jeffsOrders = orderSummary["Jeff”] if jeffsOrders { let orders: Int = jeffsOrders! } var customerName: String? = getCustomer() println("name: (customerName?.uppercaseString)") Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Pattern Matching switch milesFlown["Jeff"]! { case 0..<25000: println("Jeff is a Premier member") case 25000..<50000: println("Jeff is a Silver member") case 50000..<75000: println("Jeff is a Gold member") case 75000..<100000: println("Jeff is a Platinum member") default: println("Jeff is an Elite member") } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Pattern Matching switch reservation.fareClass { case "F", "A", "J", "C": milesBonus = 2.5 // business/first case "Y", "B": milesBonus = 2.0 // full-fare economy case "M", "H": milesBonus = 1.5 // top-tier discount economy case let fc where fc.hasPrefix("Z"): milesBonus = 0 // upgrades don't earn miles default: milesBonus = 1.0 } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Functions and Tuples func square(x: Int) -> Int { return x * x } func powers(x: Int) -> (Int, Int, Int) { return (x, x*x, x*x*x) } // The first tuple element is ignored let (_, square, cube) = powers(42) Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Closures func countIf(arr: [Int], pred: (Int) -> Bool) { var count = 0 for n in arr { if pred(n) { ++count } } return count } countIf([1, 2, 3, 4], { n in n % 2 == 0 }) var squares = [17, 3, 11, 5, 7].map({ x in x * x }) sort(&squares, { a, b in a > b }) sort(&squares) { a, b in a > b } sort(&squares) { $0 > $1 } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Swift REPL DEMO Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Classes class FrequentFlier { let name: String var miles: Double = 0 init(name: String) { self.name = name } func addMileage(fareClass: String, dist: Int) { miles += bonus(fareClass) * Double(dist) } } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Custom Properties and Observers class MileageStatus { var miles: Double = 0.0 { willSet { assert(newValue >= miles) // can't decrease one's mileage } } var status: String { get { switch miles { /* ... */ } } } } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Smart Enums enum MemberLevel { case Silver case Gold case Platinum func milesRequired() -> Int { switch self { case .Silver: return 25000 case .Gold: return 50000 case .Platinum: return 75000 } } } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Stateful Enums enum HttpResponse { case Success(body: String) case Error(description: String, statusCode: Int) } switch fakeHttpRequest("example.org") { case let .Error(desc, status) where status >= 500: println("internal server error: (desc)") case let .Error(desc, status): println("error (status) = (desc)") case .Success(let body): println("success, body = (body)") } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Extensions extension Int { var absoluteValue: Int { get { return abs(self) } } func times(action: () -> Void) { for _ in 1...self { action() } } } 5.times { println("hello") } println((-5).absoluteValue) Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Generics class Queue<T> { var items = [T]() var depth: Int { get { return items.count } } func enqueue(item: T) { items.append(item) } func dequeue() -> T { return items.removeAtIndex(0) } } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Operators struct Complex { var r: Double, i: Double func add(z: Complex) -> Complex { return Complex(r: r+z.r, i: i+z.i) } } @infix func +(z1: Complex, z2: Complex) -> Complex { return z1.add(z2) } Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Custom Operators (Oh My!) operator prefix &*^%!~ {} @prefix func &*^%!~(s: String) -> String { return s.uppercaseString } operator infix ^^ { associativity left } @infix func ^^(a: Double, b: Double) -> Double { return pow(a, b) } println(&*^%!~"hello") // prints "HELLO" println(2.0^^4.0) // prints 8.0 Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Swift and Objective-C Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Building an iOS app with Swift DEMO Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Wrapping Up • Most iOS developers are extremely excited about Swift • Swift has a much smoother learning curve and fixes many Objective-C mistakes • For the foreseeable future though, we will still use both languages Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Sasha Goldshtein blog.sashag.net @goldshtn s.sashag.net/sa-swift Thank You! Join the conversation on Twitter: @SoftArchConf #SA2014 This presentation: http://s.sashag.net/sa-swift

Swift: Apple's New Programming Language for iOS and OS X

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