Swift: An Introduction to the Language

The talk introduces Swift to someone who already understands programming but is not familiar with Objective-C. High-level concepts are presented and backed up with simple code samples. Concepts which many engineers might have never encountered, such as protocols and generics, are discussed and illustrated with examples. The talk focuses only on the Swift language and does not discuss writing apps for iOS or OS X.

Watch a video of the talk at https://www.youtube.com/watch?v=YyJshuAHl1g

Transcript

1. Swift An introduction to the language
2. Kris Arnold Shutterstock @wka @shuttertech
3. Disclaimer The only people with more than a few months experience with Swift work at Apple
4. Topics Language Design Principles Why a new language? Variables and Data Structures Flow Control Functions and Closures Classes and Protocols Structs and Enums Generics What Else? What's Missing? What's Next?
5. Language Design Principles
6. Language Design Principles Speed Safety Modern features Interoperability with Objective-C
7. Why?
8. Cruft
9. No namespaces NSObject SSIImage
10. nil NULL NSNull [NSNull null] NSNotFound Nil
11. Variables and Data Structures
12. var place = "World"
13. var place = "World" println("Hello, \(place)")
14. let place = "World" println("Hello, \(place)")
15. let place = "World" println("Hello, \(place)") place = "North America" //error!
16. var place = "World" println("Hello, \(place)") place = "North America"
17. var place = "World"
18. var place: String = "World"
19. var cities = [String]()
20. var cities = [String]() cities = ["New York", "Berlin"]
21. var cities = [String]() var cities = ["New York", "Berlin"]
22. var cities = ["New York", "Berlin"]
23. var cities = ["New York", "Berlin"] cities[0] // "New York"
24. var cities = ["New York", "Berlin"] cities[0] // "New York" cities.append("San Francisco")
25. var cities = ["New York", "Berlin"] cities[0] // "New York" cities.append("San Francisco") cities.insert("Denver", atIndex: 0)
26. var cities = ["New York", "Berlin"] cities[0] // "New York" cities.append("San Francisco") cities.insert("Denver", atIndex: 0) cities.count // 4
27. var populations = [String: Int]()
28. var populations = [String: Int]() populations = ["New York": 8_300_000, "Berlin": 3_500_000]
29. var populations = [String: Int]() populations = ["New York": 8_300_000, "Berlin": 3_500_000] populations["Denver"] = 600_000 populations["San Francisco"] = 800_000
30. var populations = [String: Int]() populations = ["New York": 8_300_000, "Berlin": 3_500_000] populations["Denver"] = 600_000 populations["San Francisco"] = 800_000 populations["New York"] // 8_300_000
31. ("nyc", 8_300_000)
32. var nameAndPop = ("nyc", 8_300_000)
33. var nameAndPop = ("nyc", 8_300_000) nameAndPop.0 // "nyc"
34. var nameAndPop = (city: "nyc", population: 8_300_000)
35. var nameAndPop = (city: "nyc", population: 8_300_000) nameAndPop.city // "nyc"
36. Optionals
37. var name: String
38. var name: String var nickname: String?
39. var name: String var nickname: String? name = nil // error
40. var name: String var nickname: String? name = nil // error nickname = nil // OK
41. populations["New York"]
42. populations["New York"] // return type: Int?
43. populations["New York"] // return type: Int? populations["Atlantis"] // return type: Int? // return value: nil
44. Flow Control
45. if … then … else for … in loops C-style for loops While loops Do-while loops
46. var nickname: String?
47. var nickname: String? … if let moniker = nickname { println("Hello \(moniker)") }
48. var nickname: String? … if let moniker = nickname { println("Hello \(moniker)") } else { println("Hello friend") }
49. var nickname: String? … println("Hello \(nickname!)")
50. var nickname: String? …
51. var nickname: String? … nickname?.extend(" :)")
52. switch statements Demo
54. Functions and Closures
55. func sayHello() -> () { println "Hello" }
56. func sayHello(name: String) -> () { println "Hello \(name)" }
57. func sayHello(name: String) -> () { println "Hello \(name)" } sayHello("Lattner") // prints "Hello Lattner"
58. func sayHello(name: String) -> () { println "Hello \(name)" } sayHello(name: "Lattner") // error!
59. func sayHello(person name: String) -> () { println "Hello \(name)" } sayHello(person: "Lattner") // correct
60. func sayHello(#name: String) -> () { println "Hello \(name)" } sayHello(name: "Lattner") // correct
61. func sayHello(name: String = "You") -> () { println "Hello \(name)" }
62. func sayHello(name: String) -> () { println "Hello \(name)" }
63. func sayHello(firstName: String, lastName: String) -> () { println "Hello \(firstName) \(lastName)" }
64. func sayHello(name: String) -> () { println "Hello \(name)" }
65. func sayHello(name: String) -> (String) { return "Hello \(name)" }
66. func sayHello(name: String) -> (String) { name += "!" return "Hello \(name)" }
67. func sayHello(name: String) -> (String) { name += "!" // error! return "Hello \(name)" }
68. func sayHello(var name: String) -> (String) { name += "!" return "Hello \(name)" }
69. func sayHello(var name: String) -> (String) { name += "!" return "Hello \(name)" } var person = "Lattner" sayHello(person)
70. func sayHello( name: String) -> (String) { name += "!" return "Hello \(name)" } var person = "Lattner" sayHello( person) println("Updated to \(person)") // "Updated to Lattner!"
71. func sayHello(inout name: String) -> (String) { name += "!" return "Hello \(name)" } var person = "Lattner" sayHello(&person) println("Updated to \(person)") // "Updated to Lattner!"
72. Closures
73. var items = [100, 2, 75, 31, 99] items.sort // items is now [2, 31, 75, 99, 100]
74. var items = [100, 2, 75, 31, 99] let sorter = { } items.sort(sorter)
75. var items = [100, 2, 75, 31, 99] let sorter = { (num1: Int, num2: Int) } items.sort(sorter)
76. var items = [100, 2, 75, 31, 99] let sorter = { (num1: Int, num2: Int) -> Bool in } items.sort(sorter)
77. var items = [100, 2, 75, 31, 99] let sorter = { (num1: Int, num2: Int) -> Bool in } items.sort(sorter)
78. var items = [100, 2, 75, 31, 99] let sorter = { (num1: Int, num2: Int) -> Bool in return num1 < num2 } items.sort(sorter)
79. var items = [100, 2, 75, 31, 99] let sorter = { (num1: Int, num2: Int) -> Bool in return num1 < num2 } items.sort(sorter)
80. var items = [100, 2, 75, 31, 99] let sorter = { (num1: Int, num2: Int) -> Bool in num1 < num2 } items.sort(sorter)
81. var items = [100, 2, 75, 31, 99] let sorter = { (num1: Int, num2: Int) in num1 < num2 } items.sort(sorter)
82. var items = [100, 2, 75, 31, 99] let sorter = { (num1, num2) in num1 < num2 } items.sort(sorter)
83. var items = [100, 2, 75, 31, 99] items.sort({(num1, num2) in num1 < num2})
84. var items = [100, 2, 75, 31, 99] items.sort({ num1, num2 in num1 < num2})
85. var items = [100, 2, 75, 31, 99] items.sort({ $0 < $1 })
86. var items = [100, 2, 75, 31, 99] items.sort({ $0 < $1 })
87. var items = [100, 2, 75, 31, 99] items.sort { $0 < $1 }
89. let list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] let evens = list.filter { $0 % 2 == 0 }
90. let list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] let evens = list.filter { $0 % 2 == 0 } let tenX = list.map { $0 * 10 }
91. let list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] let evens = list.filter { $0 % 2 == 0 } let tenX = list.map { $0 * 10 } let sum = list.reduce(0) { $0 + $1 }
92. func makeMultiplier(number: Int) -> Int -> (Int) { }
93. func makeMultiplier(number: Int) -> Int -> (Int) { }
94. func makeMultiplier(number: Int) -> Int -> (Int) { let multiplier = { } }
95. func makeMultiplier(number: Int) -> Int -> (Int) { let multiplier = { (given: Int) -> Int in return number * given } }
96. func makeMultiplier(number: Int) -> Int -> (Int) { let multiplier = { (given: Int) -> Int in return number * given } return multiplier }
97. func makeMultiplier(number: Int) -> Int -> (Int) { let multiplier = { (given: Int) -> Int in return number * given } return multiplier } let timesTwenty = makeMultiplier(20)
98. func makeMultiplier(number: Int) -> Int -> (Int) { let multiplier = { (given: Int) -> Int in return number * given } return multiplier } let timesTwenty = makeMultiplier(20) timesTwenty(3) // output == 60
99. func makeMultiplier(number: Int) -> Int -> (Int) { let multiplier = { (given: Int) -> Int in return number * given } return multiplier } let timesTwenty = makeMultiplier(20) timesTwenty(3) // output == 60 let timesFifty = makeMultiplier(50) timesFifty(3) // output == 150
101. let priority = DISPATCH_QUEUE_PRIORITY_BACKGROUND let queue = dispatch_get_gloabl_queue(priority, 0)
102. let priority = DISPATCH_QUEUE_PRIORITY_BACKGROUND let queue = dispatch_get_gloabl_queue(priority, 0) dispatch_async(queue) { longRunningOperation() longerRunningOperation() }
103. let priority = DISPATCH_QUEUE_PRIORITY_BACKGROUND let queue = dispatch_get_gloabl_queue(priority, 0) dispatch_async(queue) { longRunningOperation() longerRunningOperation() }
104. Classes and Protocols
105. class Image { }
106. class Image { var mediaId = 0 var description = "My awesome image" }
107. class Image { var mediaId = 0 var description = "My awesome image" } var myImage = Image() myImage.mediaId = 200_000
108. class Image { var mediaId var description }
109. class Image { var mediaId :Int var description :String }
110. class Image { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description } }
111. class Image { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId } }
112. class Image { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description } }
113. class Image { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description } func approveImage() -> () { println("Approving…") } }
114. class Image { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description } func approveImage() -> () { println("Approving…") } }
115. var myImage = Image( mediaId: 200_000, description: "Testing" )
116. var myImage = Image( mediaId: 200_000, description: "Testing" ) println("the description for \(myImage.mediaId) is \(myImage.description)")
117. var myImage = image( mediaId: 200_000, description: "Testing" ) println("the description for \(myImage.mediaId) is \(myImage.description)") myImage.approveImage()
118. var myImage = image( mediaId: 200_000, description: "Testing" ) println("the description for \(myImage.mediaId) is \(myImage.description)") myImage.approveImage() myImage.description = betterDescription
119. class Image { var mediaId :Int var description :String //… }
120. class Image { var mediaId :Int var description :String { } //… }
121. class Image { var mediaId :Int var description :String { didSet { } } //… }
122. class Image { var mediaId :Int var description :String { didSet { println("Changed desc to \(description)") updateAuditTrail(mediaId, description) } } //… }
123. class Image { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description } }
124. class Image { let mediaId :Int let description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description } }
125. class Image { let mediaId :Int let description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description } } //… image.description = betterDescription // error!
126. class Image { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description } }
127. class Image { var mediaId :Int var description :String var height :Int var width :Int … }
128. class Image { var mediaId :Int var description :String var height :Int var width :Int var aspectRatio :Float … }
129. class Image { var mediaId :Int var description :String var height :Int var width :Int var aspectRatio :Float { return Float(height) / Float(width) } … }
130. class Image { var mediaId :Int var description :String var height :Int var width :Int var aspectRatio :Float { return Float(height) / Float(width) } … }
131. class Image { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description } }
132. class Image: Media { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description } }
133. class Image: Media { var mediaId :Int var description :String init(mediaId: Int, description: String) { super.init() // error! self.mediaId = mediaId self.description = description } }
134. class Image: Media { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description super.init() // correct! } }
135. class Image: Media { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description super.init() // correct! } func upload() -> () { println("Uploading…") } }
136. class Image: Media { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description super.init() // correct! } override func upload() -> () { println("Uploading…") } }
137. class Image { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description super.init() // correct! } func upload() -> () { println("Uploading…") } }
138. class Image { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description super.init() // correct! } final func upload() -> () { println("Uploading…") } }
139. final class Image { var mediaId :Int var description :String init(mediaId: Int, description: String) { self.mediaId = mediaId self.description = description super.init() // correct! } func upload() -> () { println("Uploading…") } }
140. class Image { var mediaId :Int var description :String //… func upload() -> () { println("Uploading…") } }
141. class Image { var mediaId :Int private var description :String //… private func upload() -> () { println("Uploading…") } }
142. private class Image { var mediaId :Int private var description :String //… private func upload() -> () { println("Uploading…") } }
143. internal class Image { var mediaId :Int internal var description :String //… private func upload() -> () { println("Uploading…") } }
144. Extensions
145. extension Image { }
146. extension Image { func supersize () -> (UIImage) { // do scaling here } }
147. Protocols
148. class Uploader { }
149. class Uploader { func upload(uploadee: Media) { } }
150. class Uploader { func upload(uploadee: Media) { uploadee.uploadInProgress() doHTTPUpload(source: uploadee.filePath, destination: uploadee.fileName) uploadee.uploadComplete() } }
151. class Uploader { func upload(uploadee: Media) { uploadee.uploadInProgress() doHTTPUpload(source: uploadee.filePath, destination: uploadee.fileName) uploadee.uploadComplete() } }
152. class Uploader { func upload(uploadee: Media) { uploadee.uploadInProgress() doHTTPUpload(source: uploadee.filePath, destination: uploadee.fileName) uploadee.uploadComplete() } }
153. class Uploader { func upload(uploadee: Media) { uploadee.uploadInProgress() doHTTPUpload(source: uploadee.filePath, destination: uploadee.fileName) uploadee.uploadComplete() } }
154. class Uploader { func upload(uploadee: Media) { uploadee.uploadInProgress() doHTTPUpload(source: uploadee.filePath, destination: uploadee.fileName) uploadee.uploadComplete() } func doHTTPUpload(#source: String, #destination: String) -> () { // hand-waving… } }
155. class Media { var mediaId: Int = 200_000 var filePath: String = "/tmp/media.jpg" var fileType: String = "jpg" var fileName: String { return String(mediaId) + "." + fileType } func uploadInProgress() -> () { // do stuff } func uploadComplete() -> () { // do stuff } }
156. class Media { var mediaId: Int = 200_000 var filePath: String = "/tmp/media.jpg" var fileType: String = "jpg" var fileName: String { return String(mediaId) + "." + fileType } func uploadInProgress() -> () { // do stuff } func uploadComplete() -> () { // do stuff } }
157. class Uploader { func upload(uploadee: Media) { uploadee.uploadInProgress() doHTTPUpload(source: uploadee.filePath, destination: uploadee.fileName) uploadee.uploadComplete() } func doHTTPUpload(#source: String, #destination: String) -> () { // hand-waving… } }
158. class Uploader { func upload(uploadee: Media) { uploadee.uploadInProgress() doHTTPUpload(source: uploadee.filePath, destination: uploadee.fileName) uploadee.uploadComplete() } func doHTTPUpload(#source: String, #destination: String) -> () { // hand-waving… } }
159. protocol Uploadable { }
160. protocol Uploadable { var filePath: String { get } var fileName: String { get } }
161. protocol Uploadable { var filePath: String { get } var fileName: String { get } func uploadInProgress() -> () func uploadComplete() -> () }
162. class Uploader { func upload(uploadee: Media) { uploadee.uploadInProgress() doHTTPUpload(source: uploadee.filePath, destination: uploadee.fileName) uploadee.uploadComplete() } func doHTTPUpload(#source: String, #destination: String) -> () { // hand-waving… } }
163. class Uploader { func upload(uploadee: Uploadable) { uploadee.uploadInProgress() doHTTPUpload(source: uploadee.filePath, destination: uploadee.fileName) uploadee.uploadComplete() } func doHTTPUpload(#source: String, #destination: String) -> () { // hand-waving… } }
164. class Media { var mediaId: Int = 200_000 var filePath: String = "/tmp/media.jpg" var fileType: String = "jpg" var fileName: String { return String(mediaId) + "." + fileType } func uploadInProgress() -> () { // do stuff } func uploadComplete() -> () { // do stuff } }
165. class Media: Uploadable { var mediaId: Int = 200_000 var filePath: String = "/tmp/media.jpg" var fileType: String = "jpg" var fileName: String { return String(mediaId) + "." + fileType } func uploadInProgress() -> () { // do stuff } func uploadComplete() -> () { // do stuff } }
166. class CSV: Uploadable { // … }
167. Structs and Enums
168. struct CGPoint { CGFloat x; CGFloat y; };
169. struct CGPoint { CGFloat x; CGFloat y; }; struct CGSize { CGFloat width; CGFloat height; };
170. struct CGPoint { CGFloat x; CGFloat y; }; struct CGSize { CGFloat width; CGFloat height; }; struct CGRect { CGPoint origin; CGSize size; };
171. struct CGPoint { CGFloat x; CGFloat y; }; struct CGSize { CGFloat width; CGFloat height; }; struct CGRect { CGPoint origin; CGSize size; }; 16.67
172. CGPointMake CGRectMake CGSizeMake CGRectDivide CGRectInset CGRectIntegral CGRectIntersection CGRectOffset CGRectUnion CGPointEqualToPoint CGSizeEqualToSize CGRectEqualToRect CGRectIntersectsRect CGRectContainsPoint CGRectContainsRect CGRectGetMinX CGRectGetMinY CGRectGetMidX CGRectGetMidY CGRectGetMaxX CGRectGetMaxY CGRectGetHeight CGRectGetWidth CGRectIsEmpty CGRectIsNull CGRectIsInfinite
173. struct Image { }
174. struct Image { var mediaId: Int var description: String }
175. struct Image { var mediaId: Int var description: String func upload() -> () { println("Uploading image \(self.mediaId)") } }
176. struct Image { var mediaId: Int var description: String func upload() -> () { println("Uploading image \(self.mediaId)") } } var myImage = Image(mediaId: 200_000, description: "test")
177. struct Image { var mediaId: Int var description: String func upload() -> () { println("Uploading image \(self.mediaId)") } } var myImage = Image(mediaId: 200_000, description: "test") myImage.upload()
178. struct Image { var mediaId: Int var description: String func upload() -> () { println("Uploading image \(self.mediaId)") } func bang() -> () { self.description.extend("!") } }
179. struct Image { var mediaId: Int var description: String func upload() -> () { println("Uploading image \(self.mediaId)") } mutating func bang() -> () { self.description.extend("!") } }
180. Should I use a struct or a class?
181. var imageStruct = imageStr(mediaId: 200_000, description: "Flowers") var newImageStruct = imageStruct
182. var imageStruct = imageStr(mediaId: 200_000, description: "Flowers") var newImageStruct = imageStruct imageStruct.description = "Kittens"
183. var imageStruct = imageStr(mediaId: 200_000, description: "Flowers") var newImageStruct = imageStruct imageStruct.description = "Kittens" println(\(newImaegStruct.description)) // prints "Flowers"
184. var imageStruct = imageStr(mediaId: 200_000, description: "Flowers") var newImageStruct = imageStruct imageStruct.description = "Kittens" println(\(newImaegStruct.description)) // prints "Flowers" var imageObject = imageObj(mediaId: 200_000, description: "Flowers") var newImageObject = imageObject
185. var imageStruct = imageStr(mediaId: 200_000, description: "Flowers") var newImageStruct = imageStruct imageStruct.description = "Kittens" println(\(newImaegStruct.description)) // prints "Flowers" var imageObject = imageObj(mediaId: 200_000, description: "Flowers") var newImageObject = imageObject imageObject.description = "Kittens"
186. var imageStruct = imageStr(mediaId: 200_000, description: "Flowers") var newImageStruct = imageStruct imageStruct.description = "Kittens" println(\(newImaegStruct.description)) // prints "Flowers" var imageObject = imageObj(mediaId: 200_000, description: "Flowers") var newImageObject = imageObject imageObject.description = "Kittens" println(\(newImageObject.description)) // prints "Kittens"
187. Enums
188. enum Orientation { }
189. enum Orientation { case Portrait case Landscape case Square }
190. struct Image { var mediaId: Int var description: String }
191. struct Image { var mediaId: Int var description: String var orientation: Orientation }
192. struct Image { var mediaId: Int var description: String var orientation: Orientation } var myImage = Image( mediaId: 200_000, description: "Test", orientation: Orientation.Landscape )
193. struct Image { var mediaId: Int var description: String var orientation: Orientation } var myImage = Image( mediaId: 200_000, description: "Test", orientation: Orientation.Landscape )
194. struct Image { var mediaId: Int var description: String var orientation: Orientation } var myImage = Image( mediaId: 200_000, description: "Test", orientation: .Landscape )
195. enum Orientation { case Portrait case Landscape case Square }
196. enum Orientation { case Portrait case Landscape case Square func describe () -> () { } }
197. enum Orientation { case Portrait case Landscape case Square func describe () -> () { switch self { } } }
198. enum Orientation { case Portrait case Landscape case Square func describe () -> () { switch self { case .Portrait: println("Portrait orientation") case .Landscape: println("Landscape orientation") case .Square: println("What is this, Instagram?") } } }
200. struct Image { enum Orientation { case Portrait case Landscape case Square } var mediaId: Int var description: String var orientation: Orientation }
201. Generics
202. struct Lightbox { var items: [Image] mutating func addItem(item: Image) -> () { self.items.append(item) } mutating func merge(other: Lightbox) -> () { for item in other.items { self.addItem(item) } } }
203. struct Lightbox { var items: [Image] mutating func addItem(item: Image) -> () { self.items.append(item) } mutating func merge(other: Lightbox) -> () { for item in other.items { self.addItem(item) } } }
204. struct Lightbox { var items: [Image] mutating func addItem(item: Image) -> () { self.items.append(item) } mutating func merge(other: Lightbox) -> () { for item in other.items { self.addItem(item) } } }
205. struct Clipbox { var items: [Video] mutating func addItem(item: Video) -> () { self.items.append(item) } mutating func merge(other: Clipbox) -> () { for item in other.items { self.addItem(item) } } }
206. struct Clipbox { var items: [Video] mutating func addItem(item: Video) -> () { self.items.append(item) } mutating func merge(other: Clipbox) -> () { for item in other.items { self.addItem(item) } } }
207. struct Mediabox<T> { }
208. struct Mediabox<T> { var items: [T] }
209. struct Mediabox<T> { var items: [T] = [] mutating func addItem(item: T) -> () { self.items.append(item) } mutating func merge(other: Mediabox<T>) -> () { for item in other.items { self.addItem(item) } } }
210. var myLightbox = Mediabox<Image>() myLightbox.addItem(flowerImage) myLightbox.addItem(kittenImage) var myClipbox = Mediabox<Video>() myClipbox.addItem(surferVid) myClipbox.addItem(skierVid) myLightbox.addItem(surferVid) //error! myClipbox.merge(other: myLightbox) //error!
211. What Else?
212. @autoclosure automatic reference counting avoiding circular references with the weak keyword variadic parameters closed vs. open ranges associated and raw values for Enums where clauses in generics the Swift standard library operator overloading sequences and generators typealias type casting AnyObject calling Objective-C from Swift calling Swift from Objective-C
213. What's Missing?
214. Exceptions Options Meta-programming
215. What's Next?
220. developer.apple.com/swift/blog airspeedvelocity.net