iOSNeXT.ro - 10 reasons you'll love Swift - Paul Ardeleanu

10 reasons you'll love SwiftPaul Ardeleanu

TIOBE Index for Nov 2014

Why a new language?

Products

Software

App Stores

Apple needs developers

‣ maximise the number of developers

‣ keeping existing developers happy

2 ways…

‣ 30 year old language

‣ drastically different from other languages

‣ not entirely future-proof

Objective-C

How did this happen?

LLVM & Clang

gcc => llvm-gcc => llvm

Objective-C without C

Objective-C is to Swift == cat is to cattle

10 reasons you'll love Swift

1. No C

No main( ) function

No [, ] or ;

2. Modern

let http404Error = (404, "Not Found")

Tuples

let x = 1 let y = 2

let point = (x, y) (.0 1, .1 2)point.0 1

let origin = (x: 200, y: 100) origin.y

(.0 200, .1 100)100

// Original var fibonacci = 1 var prev = 0

while fibonacci < 100 { var prev_tmp = fibonacci fibonacci += prev prev = prev_tmp println(fibonacci) }

Fibonacci Tuples

// tuples var fibonacci = 1 var prev = 0

while fibonacci < 100 { (prev, fibonacci) = (fibonacci, fibonacci + prev) println(fibonacci) }

Nil coalescing operator

var b = a ?? "default value"

3. Safety

let theAnswer = 42

Constants & variables

var numberBooks = 1

var numberBooks: Int = 1

Safety - no implicit conversion

let theAnswer2 = 42

let trueAnswer = Double(theAnswer) + 0.0001

let aNumber:UInt8 = 42

let anotherNumber:Int64 = Int64(aNumber)

Safety - switch

switch (aNumber % 3, aNumber % 5 ) { case (0, 0): println("fizzbuzz") case (0, _): println("fizz") case (_, 0): println("buzz") default: println(aNumber) }

Classes vs. Structuresstruct Point { var x = 0 var y = 0 static var counter = 0 static let origin = Point() var description: String { get { switch (point.x, point.y) { case (let 0, 0): return "origin" case (let x, 0): return "on the y axis - x = \(x)" case (0, let y): return "on the x axis - y = \(y)" default: return "\(point.x)x\(point.y)" } } } func distanceToOrigin() -> Double { return … } }

class Fruit { var color: String var diameter: Int

var area: Double { get { return self.width * self.height } set(newValue) { self.width = sqrt(newValue) self.height = sqrt(newValue) } }

init(color: String, diameter: Int) { self.color = color self.diameter = diameter }

func area() -> Double { return self.width * self.height } }

Classes vs. Structures

Classes Structs

passed by reference value

inheritance ✔ ✘

initializers must be defined auto-generated member-wise initialiser

deinitializer ✔ ✘

introspection ✔ ✘

ideal for complex data relatively simple data *

Value type (Structures)

var point1 = Point(x: 100, y: 200) var point2 = point1

x: 100 y : 200point1

x: 100 y : 200point2

point1.x = 120

Value type (Structures)

var point1 = Point(x: 100, y: 200) var point2 = point1

x: 120 y : 200point1

x: 100 y : 200point2

point1.x = 120

Reference type (Classes)

var rectangle1 = Rect() rectangle1.width = 100

width: 100 height: 0rectangle1

rectangle2

var rectangle2 = rectangle1

rectangle2.width = 200

Reference type (Classes)

var rectangle1 = Rect() rectangle1.width = 100

width: 200 height: 0rectangle1

rectangle2

var rectangle2 = rectangle1

rectangle2.width = 200

4. Optionals

Optionals

var answer: Int = 42

var theAnswer: Int = nil

var theAnswer: Int? ✔

theAnswer = 42

{Some 42}

❗️

Optionals == Schrödinger’s cat

Can either:

‣ be nil

‣ contain a value

Using an optional

var theAnswer: Int?

if theAnswer != nil { var x = 4 + theAnswer }

❗️

Forced Unwrapping

var theAnswer: Int?

if theAnswer != nil { var x = 4 + theAnswer! }

Optional binding

if let answer = theAnswer { var x = 4 + answer }

Optionals

var theAnswer: Int?

theAnswer!

Optionals

var theAnswer = 42

var theAnswer: Int?

var theAnswer: Int!

- always has a value - type can be inferred

- either nil or has a value - must be unwrapped

- nil until first assignment - assumed to always have a value

Nil coalescing operator

equivalent to:

var theAnswer: Int?

var x = theAnswer ?? 12

var x = (theAnswer != nil) ? theAnswer! : 12

5. Mix & match

Swift project

Bridging

class STDataObject: NSManagedObject { @NSManaged var uuid: String? @NSManaged var sync_uuid: String? @NSManaged var is_active: NSNumber class func managedObjectContext() -> NSManagedObjectContext? { var appDelegate = UIApplication.sharedApplication().delegate as AppDelegate return appDelegate.managedObjectContext }

6. Functions as first class citizens

Function structure

func greet(title: String, person: String) -> String { return "Hello \(title) \(person)" }

function name

return type

greet("Mr.", "Paul") “Hello Mr. Paul"

parameter name

parameter type

Nestingfunc greet(var person: String) -> String { func morningGreetings(person: String) -> String { return "Good morning \(person)" } func afternoonGreetings(person: String) -> String { return "Good afternoon \(person)" } let morning = true var greeting: (String) -> String if morning { greeting = morningGreetings } else { greeting = afternoonGreetings } return greeting(person) }

greet("Paul")

Function as return typefunc greetingAt(hour: Int) -> (String) -> String { func morningGreeting(name: String) -> String { return "Good morning \(name)" } func afternoonGreeting(name: String) -> String { return "Good afternoon \(name)" } return hour < 12 ? morningGreeting : afternoonGreeting }

greetingAt(11)("Paul")

greetingAt(14)("Paul")

“Good morning Paul"

“Good afternoon Paul"

Functions are Closures

Blocks in Objective-C

NSString *(^sayHello)(NSString *);

sayHello = ^(NSString *name) { return [NSString stringWithFormat:@"Hello %@", name]; };

Person *theUser = [[Person alloc] initWithName:@"Paul"]; [theUser welcomeUserWithBlock:^(NSString *name) { NSLog(@"Hello %@", name); }];

Blocks in Objective-C

func greetWithMessage(name: String, message: (String) -> String) -> String { return message(name); }

greetWithMessage("Paul", { (name: String) -> String in return "Good morning \(name)" } )

• global function

• have name & don’t capture environment

• nested function

• have name & capture environment

• closure expressions

• no name & can capture environment

Types of Closures

7. Magic

Closures - Short Syntaxfunc greetWithMessage(name: String, message: (String) -> String) -> String { return message(name); }

greetWithMessage("Paul", { (name: String) -> String in return "Good morning \(name)" } )

greetWithMessage("Paul", { name in return "Good morning \(name)" })

greetWithMessage("Paul", { return "Good morning \($0)" })

Trailing closuresfunc greetWithMessage(name: String, message: (String) -> String) -> String { return message(name); }

greetWithMessage("Paul", { name in return "Good morning \(name)" })

greetWithMessage("Paul") { name in return "Good morning \(name)" }

greetWithMessage("Paul") { return "Good morning \($0)" }

8. Unicode

8. Emoji

Characters & Strings

let fizz = "🍹" let buzz = "🎉"

var fizzbuzz = fizz + buzz "🍹🎉"

let dog = "🐶"

Character Viewer

let 🐶 = "dog"

let 🐱 = "cat"

let 💃🐞 = "ladybug"

let ❄️🚶 = "⛄️"

Unicodelet a = "\u{103}"

let sh = "\u{15F}"

let cedilla = "\u{327}" "̧"

Extended grapheme cluster

let sh2 = "\u{73}\u{327}"

"\u{15F}" == "\u{73}\u{327}" true

ș = s + cedilla

Unicode

let sh = "\u{15F}" "ş"

let realSh = "\u{219}" "ș"

9. Playgrounds

New Playground

Empty Playground

Playground

Fibonacci

Playground - Timeline

‣ Interactive experience

‣ Immediate feedback

‣ Watch code progression through loops

‣ Easy way to

‣ prototype

‣ test snippets of code

‣ CAREFUL! Executed automatically.

Playgrounds

10. Swift REPL

REPLRead–eval–print loop

$ which swift

/usr/bin/swift

$ swift -version

Swift version 1.1 (swift-600.0.54.20)

Target: x86_64-apple-darwin14.0.0

man swift

swift -- help

$ swift Welcome to Swift! Type :help for assistance. 1> 1 + 2 $R0: Int = 3 2> "once upon a time" $R1: String = "once upon a time" 3> $R1 + " there were \($R0) bears" $R2: String = "once upon a time there were 3 bears" 4> println($R2) once upon a time there were 3 bears

‣ iOS 8 released yesterday

‣ Swift is v.1.0 as of Sept 9th

‣ Xcode 6.0.1 released yesterday

‣ Apps written in Swift started being accepted on Sept 9th

Resources

‣ iOS 8 released yesterday

‣ Swift is v.1.0 as of Sept 9th

‣ Xcode 6.0.1 released yesterday

‣ Apps written in Swift started being accepted on Sept 9th

Resources

1.No C

2.Modern

3.Safety

4.Optionals

5.Mix & match

10 reasons you’ll love Swift

6.Functions - 1st class citizens

7.Magic

8.Unicode

9.Playgrounds

10.REPL

Objective-C ➾ Swift

One more thing…

WatchKit

Thank you!

Paul Ardeleanu

pa@h24.io @pardel

iOSNeXT.ro - 10 reasons you'll love Swift - Paul Ardeleanu

Software

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