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![MAP, FILTER, REDUCE, SORT
CLOSURES
let people:[Contact] = getContacts()
let targetNames:[String] = people
.filter({ contact in contact.lastName.hasPrefix("G") })
.map({ contact in contact.fullName })
.sort()
func multipleOf(factor: Int) -> Int -> Bool {
return { (number: Int) in number % factor == 0 }
}
let isEven = multipleOf(2)
isEven(4)
// Get the sum of multiples of 3 up to 100
(1...100)
.filter(multipleOf(3))
.reduce(0, combine: +)
https://github.com/mythz/swift-linq-examples](https://image.slidesharecdn.com/thinksharpwriteswift-160513132837/75/Think-sharp-write-swift-41-2048.jpg)
Uploaded byPascal Batty
Think sharp, write swift
The document discusses the similarities between Swift and C#, highlighting features like generics, optionals, and functional programming concepts. It provides code comparisons and examples, particularly focusing on implementing the Fibonacci sequence in both languages. Additionally, it emphasizes the benefits of value types and protocol-oriented programming in Swift while offering resources for further learning.
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Think sharp, write swift
- 1. THINK SHARP, WRITESWIFT PASCAL BATTY
- 2.
- 3. I’VE ALWAYS BEEN AMAC NERD
- 6. I SAW ALOT OF PEOPLE SWITCHING
- 7.
- 8. BASED ON SCIENTIFICRESULTS THE STAGES OF SWITCHING 😫 😯 😍
- 9. iOS OS X Apps ∞ Scripts +exe OS X Ubuntu
- 10. C# Swift Object Oriented✓ ✓ Type Inference ✓ ✓ Generics ✓ ✓ Tuples ✓ ✓ Lambdas ✓ ✓ Optional Chaining ✓ ✓ String Interpolation ✓ ✓ SWIFT VS C# FEATURE COMPARISON CHART
- 11. String Interpolation ✓✓ Operator overloading ✓ ✓ Null Coalescing ✓ ✓ Variadic Parameters ✓ ✓ Optional Parameters ✓ ✓ Extensions ✓ ✓ Auto-Properties ✓ ✓ Try/Catch ✓ ✓ Cool Logo ✓
- 12. THE GOOD OLDFIBONACCI SEQUENCE LET’S COMPARE CODE func fib(n: Int) -> Int { var fib0 = 0, fib1 = 1 for var i = 2; i <= n; i++ { var tmp = fib0 fib0 = fib1 fib1 = tmp + fib1 } return n > 0 ? fib1 : 0 } static int fib(int n) { int fib0 = 0, fib1 = 1; for (int i = 2; i <= n; i++) { int tmp = fib0; fib0 = fib1; fib1 = tmp + fib1; } return (n > 0 ? fib1 : 0); } C# Swift as found on Wikibooks
- 13. SWIFT AND C# AREVERY SIMILAR
- 14. C# Swift Garbage CollectionReference Counting Interface Protocol Constructor Initializer const let Linq MapReduce Lambda Closure func<> -> SWIFT AND C# ARE KINDA SORTA SIMILAR
- 15. THE GOOD OLDFIBONACCI SEQUENCE A FEW ADJUSTMENTS func fib(n: Int) -> Int { var fib0 = 0, fib1 = 1 for var i = 2; i <= n; i++ { var tmp = fib0 fib0 = fib1 fib1 = tmp + fib1 } return n > 0 ? fib1 : 0 } Variable was never mutated; consider changing to ‘let’ constant
- 16. THE GOOD OLDFIBONACCI SEQUENCE A FEW ADJUSTMENTS func fib(n: Int) -> Int { var fib0 = 0, fib1 = 1 for var i = 2; i <= n; i++ { let tmp = fib0 fib0 = fib1 fib1 = tmp + fib1 } return n > 0 ? fib1 : 0 } ++ is deprecated: it will be removed in Swift 3
- 17. THE GOOD OLDFIBONACCI SEQUENCE A FEW ADJUSTMENTS func fib(n: Int) -> Int { var fib0 = 0, fib1 = 1 for var i = 2; i <= n; i += 1 { let tmp = fib0 fib0 = fib1 fib1 = tmp + fib1 } return n > 0 ? fib1 : 0 } C-Style for statement is deprecated and will be removed…
- 18. THE GOOD OLDFIBONACCI SEQUENCE A FEW ADJUSTMENTS func fib(n: Int) -> Int { var fib0 = 0, fib1 = 1 for i in 2...n { let tmp = fib0 fib0 = fib1 fib1 = tmp + fib1 } return n > 0 ? fib1 : 0 } Immutable value ‘i’ was never used; consider replacing with ‘_’
- 19. THE GOOD OLDFIBONACCI SEQUENCE A FEW ADJUSTMENTS func fib(n: Int) -> Int { var fib0 = 0, fib1 = 1 for _ in 2...n { let tmp = fib0 fib0 = fib1 fib1 = tmp + fib1 } return n > 0 ? fib1 : 0 } 😌
- 20. THE COMPILER IS PICKYBUT FRIENDLY
- 21.
- 22. LET US DIVEIN A LITTLE DEEPER BUILDING BLOCKS Class Properties Initializers Instance Methods Class Methods Struct Properties Initializers Instance methods Static methods Enum Properties Initializers Instance methods Static methods
- 23.
- 24. I CAN’T ASKYOU TO JUST BELIEVE ME ON THIS VALUE TYPES ARE AWESOME ▸ Immutability ensured by ‘let’ ▸ No expensive boxing/unboxing ▸ Code is more thread-safe ▸ Performance is better ▸ Functional Programming is more convenient
- 25. LET US DIVEIN A LITTLE DEEPER STANDARD TYPES ▸ Int, Float, Double ▸ Bool ▸ String, Character ▸ Array<T>, Dictionary<K: Hashable, V>, Set<T: Hashable> THESE ARE ALL STRUCTS!
- 26. ENUMERABLES YOU WON’T BELIEVEWHAT HAPPENS NEXT…
- 27. BRACE YOURSELVES… ENUMERABLES ASYOU MAY KNOW THEM enum Land { case Forest case Mountain case Swamp case Plains case Island } enum Error : Int { case NotFound = 404 case ServerError = 500 case Forbidden = 403 case Teapot = 418 } Raw value can be String, Character or any numeric type
- 28. HERE COMES! ENUMERABLES WITHASSOCIATED VALUES! enum PaymentMethod { case Cash case Check (Int) case CreditCard (CardType, Int) enum CardType { case Visa, MasterCard, Electron } func display() { switch self { case Cash: print("Paid by cash") case let Check(number): print("Paid by check #(number)") case let CreditCard(type, number): print("Paid by (type) #(number)") } } } let method = PaymentMethod.CreditCard(.Visa, 995423) method.display()
- 29. NOT OVER YET! …AND GENERICS! enum Result<T, U> { case Success(T) case Error(U) } enum Optional<T> { case Some(T) case None } indirect enum Tree<T> { case Empty case Node(T, left: Tree<T>, right: Tree<T>) }
- 30.
- 31. WHAT YOU MAYEND UP DOING… OPTIONALS IN THE WILD let answer: String = "42" let numericAnswer = Int(answer) let byOneThousand = numericAnswer * 1000 let nineThousand: Float = 9 * 1000 let vegetaSays: String = "It's over (nineThousand) !!" let nappaSays: String = "What!? " + String(nineThousand) + "?!" VALUE OF OPTIONAL TYPE ‘INT?’ NOT UNWRAPPED; DID YOU MEAN TO USE ‘!’ OR ‘?’ ? Int?
- 32. BEAR WITH METHERE OPTIONALS ▸ Like nullables for all types! ▸ Variables, constants, arguments, properties or return values ▸ You can’t use its value unless you unwrap it first ▸ If it is not Optional, it can never be nil
- 33. FORGOT TO CHECKNULLABILITY? WON’T LET YOU USE THE VALUE
- 34. DO YOU KNOWTHE ‘MAYBE’ MONAD ? UNWRAPPING THE OPTIONAL 42 let answer: String = getAnswer() let numericAnswer: Int? = Int(answer) processNumericAnswer(numericAnswer) ??? Int? Int nil
- 35. DO YOU KNOWTHE ‘MAYBE’ MONAD ? UNWRAPPING THE OPTIONAL 42 let answer: String = getAnswer() let numericAnswer: Int? = Int(answer) if let realAnswer: Int = numericAnswer { processNumericAnswer(realAnswer) } else { print("Please give a number") } nil Int?Int?
- 36. NOT EVERYTHING ISCOMPULSORY OPTIONAL PROPERTIES struct Contact { var firstName:String var middleName:String? var lastName:String var emailAddress:String var emailVerified:Bool }
- 37. THAT’S A LOTOF PUNCTUATION! NULL COALESCING AND OPTIONAL CHAINING let answer: String = getAnswer() let numericAnswer: Int? = Int(answer) let sanitizedAnswer: Int = numericAnswer ?? 1 processNumericAnswer(sanitizedAnswer) let contact: Contact? = getContact() let email: String? = contact?.emailAddress ?? ?.
- 38. FAMOUS LAST WORDS… FORCEUNWRAP & IMPLICITLY UNWRAPPED OPTIONALS ! « I KNOW WHAT I’M DOING. IF YOU ENCOUNTER AN UNEXPECTED NIL JUST CRASH AT RUNTIME »
- 39.
- 40. PUT SOME LOGICINSIDE YOUR TYPES! FUN WITH PROPERTIES struct Contact { var firstName: String var middleName: String? var lastName: String let securityNumber: Int var fullName: String { if let initial = middleName?.characters.first { return "(firstName) (initial). (lastName)" } else { return "(firstName) (lastName)" } } var emailVerified: Bool var emailAddress: String { didSet { emailVerified = false } } }
- 41. MAP, FILTER, REDUCE,SORT CLOSURES let people:[Contact] = getContacts() let targetNames:[String] = people .filter({ contact in contact.lastName.hasPrefix("G") }) .map({ contact in contact.fullName }) .sort() func multipleOf(factor: Int) -> Int -> Bool { return { (number: Int) in number % factor == 0 } } let isEven = multipleOf(2) isEven(4) // Get the sum of multiples of 3 up to 100 (1...100) .filter(multipleOf(3)) .reduce(0, combine: +) https://github.com/mythz/swift-linq-examples
- 42.
- 43. IMAGINE THE POSSIBILITIES… EXTENSIONS& PROTOCOLS extension Contact { func composeEmailBoilerplate() -> String { … } var abbreviatedName: String { … } } protocol StringSerializable { func serialize() -> String } extension StringSerializable { func serialize() -> String { return "" } } extension Contact: StringSerializable { func serialize() -> String { … } }
- 44.
- 45.
- 46. YOU’VE GOT TOSTART SOMEWHERE YOUR LEARNING ENVIRONMENT OS X Ubuntu Windows Xcode Playground REPL Ubuntu Bash
- 47. WHEREVER YOU ARE SWIFTSANDBOX https://swiftlang.ng.bluemix.net
- 48. ONE OF THEPERKS OF DOING SWIFT ON THE MAC PLAYGROUND
- 49. BECAUSE WE DON’THAVE THE TIME TO SEE EVERYTHING LEARN ▸ Updated eBook from Apple ▸ Available for free ▸ on iBooks ▸ on swift.org ▸ swiftdoc.org is a nice and fast documentation website
- 50.
- 51.
- 52. A POLARIZING ASPECT ARGUMENTNAMING (1...100) .filter(multipleOf(3)) .reduce(0, combine: +) array.insert(0, 4) array.insert(0, atIndex: 4)
- 53.
- 54.
- 55. A CONVENTION-CREATING KEYWORD GUARD funcmultipleOf(factor: Int) -> Int -> Bool { return { (number: Int) in number % factor == 0 } }
- 56. A CONVENTION-CREATING KEYWORD GUARD funcmultipleOf(factor: Int) -> Int -> Bool { guard factor != 0 else { return { _ in false } } return { (number: Int) in number % factor == 0 } }
- 57.
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- 59.
- 60.
- 61. THANK YOU 💙 PascalBatty @scalbatty scalbatty blog.soat.fr https://github.com/scalbatty/Think-Sharp-Write-Swift