Swift Thinking

Transcript

• 1. Swift Thinking @NatashaTheRobot
• 2. Back to December #import <Foundation/Foundation.h> int main(int argc, const char * argv[]) { @autoreleasepool { // insert code here... NSLog(@"Hello, World!"); } return 0; }
• 3. println("Hello, World!")
• 4. —Optionals?! —Value Types —Higher-order functions
• 5. Optionals?!
• 6. "~40% of bugs shipped to customers in the last three years would have been caught immediately by using Swift" - Sunset Lake Software
• 7. enum Optional<T> { case Some(T) case None }
• 8. let tSwiftAlbums = [ 2014 : "1989", 2012: "Red", 2010: "Speak Now", 2008: "Fearless", 2006: "Taylor Swift"] let possibleAlbumFrom2011: String? = tSwiftAlbums[2011] let possibleAlbumFrom2014: String? = tSwiftAlbums[2014]
• 9. let tSwiftAlbums = [ 2014 : "1989", 2012: "Red", 2010: "Speak Now", 2008: "Fearless", 2006: "Taylor Swift"] let possibleAlbumFrom2014: String? = tSwiftAlbums[2014] if possibleAlbumFrom2014 == .None { println("Taylor Swift had no albums in 2014") } else { let albumFrom2014 = possibleAlbumFrom2014! println("Taylor Swift's 2014 album was (albumFrom2014)") }
• 10. let tSwiftAlbums = [ 2014 : "1989", 2012: "Red", 2010: "Speak Now", 2008: "Fearless", 2006: "Taylor Swift"] if let albumFor2014 = tSwiftAlbums[2014] { println("Taylor Swift's 2014 album was (albumFor2014)") } else { println("Taylor Swift had no albums in 2014") }
• 11. Value Types
• 12. —structs —enums —(tuples)
• 13. class Album { let title: String let artist: String var copiesSold: Int init(title: String, artist: String, copiesSold: Int) { self.title = title self.artist = artist self.copiesSold = copiesSold } }
• 14. let tSwift1989 = Album(title: "1989", artist: "Taylor Swift", copiesSold: 4505000) func another1000Sales(forAlbum album: Album) { album.copiesSold += 1000 } another1000Sales(forAlbum: tSwift1989) tSwift1989.copiesSold // 4,506,000
• 15. struct Album { let title: String let artist: String var copiesSold: Int }
• 16. let tSwift1989 = Album(title: "1989", artist: "Taylor Swift", copiesSold: 4505000) func another1000Sales(var forAlbum album: Album) { album.copiesSold += 1000 album.copiesSold // 4,506,000 } another1000Sales(forAlbum: tSwift1989) tSwift1989.copiesSold // 4,505,000
• 17. Use a value type when: —Comparing instance data with == makes sense —You want copies to have independent state —The data will be used in code across multiple threads Swift Blog: Value and Reference Types
• 18. Use a reference type (e.g. use a class) when: —Comparing instance identity with == makes sense —You want to create shared, mutable state Swift Blog: Value and Reference Types
• 19. "Almost all types in Swift are value types, including arrays, dictionaries, numbers, booleans, tuples, and enums. Classes are the exception rather than the rule." - Functional Swift Book
• 20. $ grep -e "^struct " swift.md | wc -l 81 $ grep -e "^enum " swift.md | wc -l 8 $ grep -e "^class " swift.md | wc -l 3
• 21. Higher-order Functions
• 22. a higher-order function is a function that does at least one of the following: —takes one or more functions as an input —outputs a function - Wikipedia
• 23. Array —map —reduce —filter —flatMap
• 24. struct Song { let title: String let album: String } let tSwiftSongs = [ Song(title: "Blank Space", album: "1989"), Song(title: "All You Had to Do Was Stay", album: "Red"), Song(title: "Back to December", album: "Speak Now"), Song(title: "All You Had to Do Was Stay", album: "1989"), Song(title: "Begin Again", album: "Red"), Song(title: "Clean", album: "1989"), Song(title: "Love Story", album: "Fearless"), Song(title: "Shake It Off", album: "1989"), Song(title: "Bad Blood", album: "1989") ]
• 25. struct tSwift1989Album { let title = "1989" var songs = [Song]() }
• 26. class tSwift1989Album { let title = "1989" var songs = [Song]() func add1989Songs() { for song in tSwiftSongs { if song.album == "1989" { songs.append(song) } } } }
• 27. let album = tSwift1989Album() album.add1989Songs() album.songs.count // 5
• 28. let album = tSwift1989Album() album.add1989Songs() album.songs.count // 5 // MUCH FURTHER DOWN album.add1989Songs()
• 29. let album = tSwift1989Album() album.add1989Songs() album.songs.count // 5 // MUCH FURTHER DOWN album.add1989Songs() album.songs.count // 10
• 30. let album = tSwift1989Album() album.add1989Songs() album.songs.count // 5 album.add1989Songs() album.songs.count // 10 album.add1989Songs() album.songs.count // 15 album.add1989Songs() album.songs.count // 20
• 31. /// Return an `Array` containing the elements `x` of `self` for which /// `includeElement(x)` is `true` func filter(includeElement: (T) -> Bool) -> [T]
• 32. class tSwift1989Album { let title = "1989" var songs = [Song]() func add1989SongsWithFilter() { songs = tSwiftSongs.filter({ song in song.album == "1989"}) } }
• 33. songs = tSwiftSongs.filter({ song in song.album == "1989"})
• 34. songs = tSwiftSongs.filter({ song in song.album == "1989"}) songs = tSwiftSongs.filter({ $0.album == "1989"})
• 35. songs = tSwiftSongs.filter({ song in song.album == "1989"}) songs = tSwiftSongs.filter({ $0.album == "1989"}) songs = tSwiftSongs.filter { $0.album == "1989"}
• 36. let album = tSwift1989Album() album.add1989SongsWithFilter() album.songs.count // 5 album.add1989SongsWithFilter() album.songs.count // 5 album.add1989SongsWithFilter() album.songs.count // 5 album.add1989SongsWithFilter() album.songs.count // 5 album.add1989SongsWithFilter() album.songs.count // 5
• 37. Swift Thinking —Optionals?! —Value Types —Higher-order functions
• 38. Questions?! @NatashaTheRobot