Taking Swift into production

Have you already embraced Swift? We at Q42 decided to adopt Swift as soon as possible. With this talk we’ll share our learnings with the new language while building the new PostNL app. Learn about our frustrations, glorious moments and touch upon some practical Functional Programming. Of course the famous SourceKitService crashes and how we managed to use a new language for such a high profile project will also have its place. After this talk you will know wether you want to use Swift in your projects and have practical tips that will kickstart you when using Swift.

As presented at mdevcon:
http://mdevcon.com/posts/2015/01/09/mathijs-kadijk/

Want to know more about Q42 and Swift?
Check out: http://q42.com/swift

Transcript

1. Taking Swift into production 1
2. Mathijs Kadijk Q42 2
4. Latest creation: A Swift app 4
6. Screenshots at: https://itunes.apple.com/ nl/app/id513218878? mt=8 6
7. Using Swift Taking the decision 7
8. We ❤️‍ new tech 8
10. Take a step forward 10
11. You can always go back! 11
12. Is Swift too beta? Lets see... 12
13. Project setup 13
14. Apple frameworks ! 14
15. CocoaPods ! 15
16. Swift frameworks + iOS 7 ! 16
17. Xcode version 6.1.1 (6A2008a) 17
18. Covered our bases? Time to code! 18
19. Where are my nils? 19
20. Optionals 20
21. Optionals var greeting: String? if let greeting = greeting { println("\(greeting)") } 21
22. Optionals: if let pyramid if let availableOptions = availableOptions { if let otherDay = availableOptions.otherDay { if let timeTable = otherDay.timeTable { // Do something with timeTable } } } 22
23. Optionals: Chaining if let timeTable = availableOptions?.otherDay?.timeTable { // Do something with timeTable } 23
24. Optionals: Multiple unwrap if let greeting = greeting, name = name { println("\(greeting) \(name)") } Swift 1.2 only! 24
25. Optionals 25
26. Optional Just an enum 26
27. Search result screen Four states 27
28. How do we model this? 28
29. Result screen: enum enum ShipmentResultViewModel { case Pending case NotFound case Details case Error } 29
30. Result screen: enum enum ShipmentResultViewModel { case Pending case NotFound case Details case Error } var state: ShipmentResultViewModel = .Pending var request: ShipmentAddToMailboxRequest var shipment: Shipment? var error: NSError? 30
31. Enums Can hold data 31
32. Result screen: enum enum ShipmentResultViewModel { case Pending case NotFound(ShipmentAddToMailboxRequest) case Details(ShipmentAddToMailboxRequest, Shipment) case Error(ShipmentAddToMailboxRequest, NSError) } var state: ShipmentResultViewModel = .Pending 32
33. Result screen: Using the enum switch resultViewModel { case .Pending: println("Pending") case let .NotFound(request): println("NotFound: \(request)") case let .Details(request, shipment): println("Details: \(request) \(shipment)") case let .Error(request, error) println("Details: \(request) \(error)") } 33
34. State is evil Enums make it easier 34
35. Working with Cocoa 35
36. AnyObjects everywhere func dequeueReusableCellWithIdentifier(/* ... */) -> AnyObject var subviews: [AnyObject] { get } func constraints() -> [AnyObject] func addConstraints(_ constraints: [AnyObject]) func subpathsAtPath(_ path: String) -> [AnyObject]? func indexPathsForRowsInRect(_ rect: CGRect) -> [AnyObject] 36
37. NSError ** aka NSErrorPointer 37
38. NSError in Swift var optionalError: NSError? if let object = existingObjectWithID(managedObjectID, error: &optionalError) { println("Object found: \(object)") } else if let error = optionalError { println("An error occured: \(error)") } 38
39. NSError in Swift var optionalError: NSError? if let object = existingObjectWithID(managedObjectID, error: &optionalError) { if let object = deleteObject(object, error: &optionalError) { println("Object deleted!") } else if let error = optionalError { println("An error occured: \(error)") } } else if let error = optionalError { println("An error occured: \(error)") } 39
40. Introducing Result type 40
41. Result enum enum Result<T> { case Success(T) case Failure(NSError) } 41
42. Result enum From: func existingObjectWithID(_ objectID: NSManagedObjectID, error error: NSErrorPointer) -> NSManagedObject? To: func existingObjectWithID(_ objectID: NSManagedObjectID) -> Result<NSManagedObject> 42
43. Result enum switch existingObjectWithID(managedObjectID) { case let .Success(object): println("Object found: \(object)") case let .Failure(error): println("An error occured: \(error)") } 43
44. Result enum switch existingObjectWithID(managedObjectID) { case let .Success(object): switch deleteObject(object) { case .Success: println("Object deleted!") case let .Failure(error): println("An error occured: \(error)") } case let .Failure(error): println("An error occured: \(error)") } 44
45. Result enum with map extension Result { func map<U>(f: T -> U) -> Result<U> { switch self { case let .Success(x): return .Success(f(x)) case let .Failure(x): return .Failure(x) } } } 45
46. Error handling with map let findResult = existingObjectWithID(managedObjectID) let deleteResult: Result<Result<Void>> = findResult.map(deleteObject) 46
47. Result enum with flatten func flatten<T>(result: Result<Result<T>>) -> Result<T> { switch result { case let .Success(x): return x case let .Failure(x): return .Failure(x) } } 47
48. Error handling with map + flatten let findResult = existingObjectWithID(managedObjectID) let deleteResult: Result<Void> = flatten(findResult.map(deleteObject)) 48
49. Result enum with flatmap extension Result { func flatMap<U>(f: T -> Result<U>) -> Result<U> { return flatten(map(f)) } } 49
50. Error handling with flatmap let result = existingObjectWithID(managedObjectID) .flatMap(deleteObject) 50
51. Functional style error handling switch existingObjectWithID(managedObjectID) .flatMap(deleteObject) { case .Success: println("Object deleted!") case let .Failure(error): println("An error occured: \(error)") } 51
52. Functional patterns Daily use 52
53. Sometimes Swift tells you T0 != T1 != T2 != T3 53
54. Swift closure swizzling 54
55. Time spend on bugs Not too much 55
56. Time spend compiling An aweful lot 56
57. Swift learning curve Few weeks 57
58. Is Swift too beta? No! 58
59. New project Swift it! 59
60. Convince collegues? Show & Play 60
61. Convince your boss? Future with less bugs 61
62. Taking Swift into production 62