The Bright Future of Swift

This talk was presented at dotSwift 2016, which took place in Paris on January 29, 2016.

Transcript

1. The Bright Future of Swift
4. The Future of Swift
5. I can see clearly now, where Swift will go I can see all obstacles in my way Gone are the dark clouds that had me blind It’s gonna be a bright, bright sun-shiny day. - Johnny Nash (emphasis mine)
6. Plan for the future, but live in the present
7. class Box<T> { let value: T init(_ value: T) { self.value = value } } enum Result<T, E> { case Success(Box<T>) case Failure(Box<E>) }
8. WWDC
9. Plan for the future, but live in the present
12. Plan for the future, but live in the present
13. session.dataTaskWithURL(url) { (data, response, error) -> Void in // process the response }
14. session.dataTaskWithURL(url) { (data, response, error) -> Void in // process the response dispatch_async(dispatch_get_main_queue()) { // update UI } } session.delegateQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
15. func getBirds(completionHandler: [(Bird, UIImage)] -> Void) { session.dataTaskWithURL(NSURL(string: "http://developer.apple.com/naming.json")!) { (data, response, error) -> Void in if let data = data, json = self.birdsJsonFromResponseData(data) { var result: [(Bird, UIImage)] = [] for (index, bird) in json.enumerate() { if let bird = self.parseBird(bird) { self.getImage(bird) { image in result.insert((bird, image), atIndex: min(result.count, index)) if result.count == json.count { dispatch_async(dispatch_get_main_queue()) { completionHandler(result) } } } } } } }.resume() }
16. func getBirds(completionHandler: [(Bird, UIImage)] -> Void) { session.dataTaskWithURL(NSURL(string: "http://developer.apple.com/naming.json")!) { (data, response, error) -> Void in if let data = data, json = self.birdsJsonFromResponseData(data) { var result: [(Bird, UIImage)] = [] for (index, bird) in json.enumerate() { if let bird = self.parseBird(bird) { self.getImage(bird) { image in result.insert((bird, image), atIndex: min(result.count, index)) if result.count == json.count { dispatch_async(dispatch_get_main_queue()) { completionHandler(result) } } } } } } }.resume() }
17. Introducing Futures (aka Promises)
18. func getImage(name: String, completionHandler: UIImage -> Void)
19. func getImage(name: String) -> Future<UIImage, Error>
20. getImage("swift").onSuccess { image in // do something with the image }
21. getImage("swift").onSuccess { image in // do something with the image }.onSuccess { image in // do something else with the image }
22. getImage("swift").onSuccess { image in // do something with the image }.onSuccess { image in // do something else with the image }.onFailure { error in // handle the error }
23. func getImage(name: String) -> Future<UIImage, Error> { return Future { completion in session.fetchImage(name, completionHandler: { image in completion(.Success(image)) }) } }
24. getImage("swift").onSuccess { image in // do something with the image }.onSuccess { image in // do something else with the image }.onFailure { error in // handle the error }
25. let image = getImage("swift") // image is a Future<UIImage, Error>
26. let image = getImage("swift") // image is a Future<UIImage, Error> image.zip(getDetails("swift")).onSuccess { image, details in // do something with the image and the details }
27. let image = getImage("swift") // image is a Future<UIImage, Error> image.zip(getDetails("swift")).onSuccess { image, details in // do something with the image and the details }.onFailure { error in // deal with the error }
28. getDetails("swift")
29. getDetails("swift").map { details in return details.substringToIndex( details.startIndex.advancedBy(30) ) }
30. getDetails("swift").map { details in return details.substringToIndex( details.startIndex.advancedBy(30) ) }.map { summary in return summary + "... Read more" }
31. getDetails("swift").map { details in return details.substringToIndex( details.startIndex.advancedBy(30) ) }.map { summary in return summary + "... Read more" } // subtitle is a Future<String, Error> let subtitle =
32. Asynchronous values as first-class citizens
33. getDetails("swift").map { details in return details.substringToIndex( details.startIndex.advancedBy(30) ) }.map { summary in return summary + "... Read more" } // subtitle is a Future<String, Error> let subtitle =
34. func +<E>(lhs: Future<String, E>, rhs: String) -> Future<String, E> getDetails("swift").map { details in return details.substringToIndex( details.startIndex.advancedBy(30) ) }.map { summary in return summary + "... Read more" } // subtitle is a Future<String, Error> let subtitle =
35. func +<E>(lhs: Future<String, E>, rhs: String) -> Future<String, E> { return lhs.map { l in return l + rhs } } getDetails("swift").map { details in return details.substringToIndex( details.startIndex.advancedBy(30) ) }.map { summary in return summary + "... Read more" } // subtitle is a Future<String, Error> let subtitle =
36. getDetails("swift").map { details in return details.substringToIndex( details.startIndex.advancedBy(30) ) } + "... Read more" func +<E>(lhs: Future<String, E>, rhs: String) -> Future<String, E> { return lhs.map { l in return l + rhs } } let subtitle =
37. extension FutureType where Value == String { func substringToIndex(index: Int) -> Future<String, Value.Error> { return map { str in return str.substringToIndex(str.startIndex.advancedBy(index)) } } } getDetails("swift").map { details in return details.substringToIndex( details.startIndex.advancedBy(30) ) } + "... Read more" let subtitle =
38. getDetails("swift").substringToIndex(30) + "... Read more" extension FutureType where Value == String { func substringToIndex(index: Int) -> Future<String, Value.Error> { return map { str in return str.substringToIndex(str.startIndex.advancedBy(index)) } } } let subtitle =
39. // subtitle is a Future<String, Error> getDetails("swift").substringToIndex(30) + "... Read more" let subtitle =
40. cell.detailTextLabel!.text = subtitle // subtitle is a Future<String, Error> getDetails("swift").substringToIndex(30) + "... Read more" let subtitle =
41. public enum Optional<Wrapped>
42. The Future’s 20%
43. func getImage(url: String) -> async UIImage
44. func getImage(url: String) -> async UIImage { let data: async NSData = session.fetch(url) return UIImage(data: data) }
45. func setImage(url: String) -> async Void { let image: async UIImage = getImage(url) when let image = image { imageView.image = image } }
46. func setImage(url: String) -> Future<Void, Error> { let image: Future<UIImage, Error> = getImage(url) return image.onSuccess { image in imageView.image = image }.asVoid() }
47. func setImage(url: String) -> async Void { let image: async UIImage = getImage(url) when let image = image { imageView.image = image } }
48. func setImage(url: String) { let image: async UIImage = getImage(url) if let image = image { imageView.image = image } }
49. func setImage(url: String) { let image: async UIImage = getImage(url) imageView.image = image! }
50. The Future’s 20% *
52. The thread-safety layer Copyable Reentrant Code Gateway Annotation
53. @_semantics("swift.concurrent.launch") func async<A>(args: A, task: A -> Void) { // launch the task } async(100, fibonacci) The thread-safety layer Copyable Reentrant Code Gateway Annotation
54. Plan for the future, but live in the present
55. Thank you! @thomvis88 https://github.com/Thomvis/BrightFutures http://highstreetapp.com