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

10 reasons you'll love Swift
Paul Ardeleanu
© 2014 Hello24 Ltd.
hello24.com

TIOBE Index for Nov 2014
Slide 5 Hello24 Ltd. (c) 2014

TIOBE Index for Nov 2014
Slide 6 Hello24 Ltd. (c) 2014

Hello24 Ltd. (c) 2014
AAPL

Hello24 Ltd. (c) 2014
Products

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Software

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App Stores

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Apps

Slide Hello24 Ltd. (c) 2014
‣ maximise the number of developers
‣ keeping existing developers happy
14
2 ways…

‣ 30 year old language
‣ drastically different from other languages
‣ not entirely future-proof
15
Objective-C

LLVM & Clang
gcc => llvm-gcc => llvm

Swift
Objective-C without C
19
Objective-C is to Swift == cat is to cattle

2 Hello24 Ltd. (c) 2014
No main( ) function

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No [, ] or ;

Module 02 Slide Hello24 Ltd. (c) 2014
let http404Error = (404, "Not Found")
25
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)
}
26
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"
Module 02 Slide 2 7 Hello24 Ltd. (c) 2014

let theAnswer = 42
29
Constants & variables
var numberBooks = 1
var numberBooks: Int = 1

Safety - no implicit conversion
Slide 3 0 Hello24 Ltd. (c) 2014
let theAnswer2 = 42
let trueAnswer = Double(theAnswer) + 0.0001
let aNumber:UInt8 = 42
let anotherNumber:Int64 = Int64(aNumber)

1 Hello24 Ltd. (c) 2014
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. Structures
struct 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 = (case (0, let y):
return "on the x axis - 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
point1.x = 120
point1 y : 200
x: 100
point2 y : 200

Value type (Structures)
var point1 = Point(x: 100, y: 200)
var point2 = point1
x: 120
point1.x = 120
point1 y : 200
x: 100
point2 y : 200

Reference type (Classes)
var rectangle1 = Rect()
rectangle1.width = 100
var rectangle2 = rectangle1
width: 100
rectangle1 height: 0
rectangle2

Reference type (Classes)
var rectangle1 = Rect()
var rectangle2 = rectangle1
width: 200
rectangle1 height: 0
rectangle2

❗️
Optionals
var answer: Int = 42
var theAnswer: Int = nil
var theAnswer: Int? ✔
theAnswer = 42
nil
{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?
var x = 4 + theAnswer!
}
✔

Optional binding
if let answer = theAnswer {
var x = 4 + answer
}
}
no !

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
var theAnswer: Int?
var x = theAnswer ?? 12
equivalent to:
var x = (theAnswer != nil) ? theAnswer! : 12

0 Hello24 Ltd. (c) 2014
Swift project

1 Hello24 Ltd. (c) 2014
Bridging

2 Hello24 Ltd. (c) 2014
Bridging

3 Hello24 Ltd. (c) 2014
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
function
name
parameter
name
parameter
type
func greet(title: String, person: String) -> String {
return "Hello (title) (person)"
}
return
type
greet("Mr.", "Paul") “Hello Mr. Paul"

Nesting
func 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 type
func 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"

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
}
)

• global function
• have name & don’t capture environment
• nested function
• have name & capture environment
• closure expressions
• no name & can capture environment
61
Types of Closures

Closures - Short Syntax
func greetWithMessage(name: String, message: (String) -> String) -> String {
}
greetWithMessage("Paul",
{ (name: String) -> String in
}
)
greetWithMessage("Paul", { name in
})
greetWithMessage("Paul", {
return "Good morning ($0)"
})

Trailing closures
func greetWithMessage(name: String, message: (String) -> String) -> String {
}
greetWithMessage("Paul", { name in
})
greetWithMessage("Paul") { name in
}
greetWithMessage("Paul") { return "Good morning ($0)" }

Characters & Strings
let dog = ""
let fizz = ""
let buzz = ""
var fizzbuzz = fizz + buzz ""

Character Viewer

let  = "dog"
let  = "cat"
let  = "ladybug"
let ❄️ = "⛄️"
69
Emoji

"ş"
Unicode
let a = "u{103}"
let sh = "u{15F}"
"ă"
"ş"
Extended grapheme cluster
ș = s + cedilla
let cedilla = "u{327}" "̧"
let sh2 = "u{73}u{327}"
"u{15F}" == "u{73}u{327}" true

Unicode
let sh = "u{15F}" "ş"
let realSh = "u{219}" "ș"

6 Hello24 Ltd. (c) 2014
New Playground

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Empty Playground

8 Hello24 Ltd. (c) 2014
Playground

9 Hello24 Ltd. (c) 2014
Playground

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Fibonacci

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Fibonacci

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Fibonacci

3 Hello24 Ltd. (c) 2014
Playground - Timeline

‣ Interactive experience
‣ Immediate feedback
‣ Watch code progression through loops
‣ Easy way to
‣ prototype
‣ test snippets of code
‣ CAREFUL! Executed automatically.
84
Playgrounds

6 Hello24 Ltd. (c) 2014
REPL
Read–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

7 Hello24 Ltd. (c) 2014
man swift

8 Hello24 Ltd. (c) 2014
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
89
REPL

‣ 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
90
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
91
Resources

10 reasons you’ll love Swift
6.Functions - 1st class citizens
7.Magic
8.Unicode
9.Playgrounds
10.REPL
1.No C
2.Modern
3.Safety
4.Optionals
5.Mix & match
92

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

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