Objective-C & Swift: Interoperability Tips and Tricks

Talk given at Wizeline Academy in Mexico City.

Transcript

2. Oscar Swanros, iOS Engineering @ PSPDFKit @Swanros Objective-C / Swift Interoperability
5. Large background image caption.
7. Agenda • Swift considerations • Objective-C considerations • Tips and tricks • Demo • Final thoughts
8. ✋if Objective-C is your main language.
9. ✋if Swift is your main language.
10. What makes Swift special? Swift Considerations
11. • Fun to write
12. • Fun to write • Really expressive
13. • Fun to write • Really expressive • Type safe!
14. • Fun to write • Really expressive • Type safe! • No ABI stability just yet
15. Why you don’t want to ditch it, just yet. Objective-C Considerations
16. • You already know Objective-C
17. • You already know Objective-C • ABI stability
18. • You already know Objective-C • ABI stability • Flexibility
19. • You already know Objective-C • ABI stability • Flexibility • Less work when trying to interact with low- level APIs.
20. Why mix both?
21. • Legacy project trying to incorporate new features?
22. • Legacy project trying to incorporate new features? • New project using legacy dependencies?
23. • Legacy project trying to incorporate new features? • New project using legacy dependencies? • Someone on your team doesn't know one of the two?
24. Tips and tricks
25. Weak references
26. @protocol WZProcessorDelegate -(void)processorDidFinish:(WZProcessor *)processor; @end @interface WZProcessor @property (nonatomic, weak) id<WZProcessorDelegate> delegate; @end
27. @protocol WZProcessorDelegate -(void)processorDidFinish:(WZProcessor *)processor; @end @interface WZProcessor @property (nonatomic, weak) id<WZProcessorDelegate> delegate; @end
28. protocol WZProcessorDelegate { func processorDidFinish(processor: WZProcessor) } class WZProcessor { var delegate: WZProcessorDelegate? } ⚠
29. protocol WZProcessorDelegate: class { func processorDidFinish(processor: WZProcessor) } class WZProcessor { weak var delegate: WZProcessorDelegate? }
30. protocol WZProcessorDelegate: class { func processorDidFinish(processor: WZProcessor) } class WZProcessor { weak var delegate: WZProcessorDelegate? }
31. @objc
32. @objc • Expose Swift API to Objective-C • Make concrete Swift interfaces for Objective-C • Access the Objective-C runtime from Swift
33. class WZManager { init(identifier: WZIdentifier) { // ... } func register(observer: WZObservable) { // ... } } Exposing API
34. @objc class WZManager { @objc init(identifier: WZIdentifier) { // ... } @objc func register(observer: WZObservable) { // ... } } Exposing API All types involved need to be representable in Objective-C
35. @interface WZBaseObject: NSObject <NSCoder> //... @end Concrete Interfaces class WZIterator: WZBaseObject { // ... }
36. @interface WZBaseObject: NSObject <NSCoder> //... @end Concrete Interfaces @objc(WZIterator) class WZIterator: WZBaseObject { // ... }
37. Access the Objective-C Runtime private extension Selector { static let didTapLoginButton = #selector(VC.didTapLoginButton) } class VC: UIViewController { @objc func didTapLoginButton() { } override func viewDidLoad() { super.viewDidLoad() button.addTarget(self, action: .didTapLoginButton, action: .to } }
38. Enumerations
39. enum cup_sizes { xs = 0, s m, l, xl };
40. typedef NS_ENUM(NSUInteger, WZCupSize) { WZCupSizeExtraSmall = 0, WZCupSizeSmall, WZCupSizeMedium, WZCupSizeLarge, WZCupSizeExtraLarge };
41. typedef NS_ENUM(NSUInteger, WZCupSize) { WZCupSizeExtraSmall = 0, WZCupSizeSmall, WZCupSizeMedium, WZCupSizeLarge, WZCupSizeExtraLarge };
42. enum CupSize: Int { case extraSmall case small case medium case large case extraLarge }
43. Extensible Enumerations
44. typedef NS_ENUM(NSUInteger, WZShirtPattern) { WZShirtPatternFlowers = 0, WZShirtPatternPlaid, WZShirtPatternSquares, WZShirtPatternDots, WZShirtPatternLines };
45. // Base definition typedef NSString *WZShirtPattern NS_TYPED_EXTENSIBLE_ENUM; // Specializations extern WZShirtPattern const WZShirtPatternFlowers; extern WZShirtPattern const WZShirtPatternPlaid; extern WZShirtPattern const WZShirtPatternSquares; extern WZShirtPattern const WZShirtPatternDots; extern WZShirtPattern const WZShirtPatternLines; struct ShirtPattern { typealias RawValue = String init(_ rawValue: RawValue) init(rawValue: rawValue) var rawValue: RawValue { get } static var flowers: ShirtPattern { get } static var plaid: ShirtPattern { get } static var squares: ShirtPattern { get } static var dots: ShirtPattern { get } static var lines: ShirtPattern { get } }
46. // Base definition typedef NSString *WZShirtPattern NS_TYPED_EXTENSIBLE_ENUM; // Specializations extern WZShirtPattern const WZShirtPatternFlowers; extern WZShirtPattern const WZShirtPatternPlaid; extern WZShirtPattern const WZShirtPatternSquares; extern WZShirtPattern const WZShirtPatternDots; extern WZShirtPattern const WZShirtPatternLines; struct ShirtPattern { typealias RawValue = String init(_ rawValue: RawValue) init(rawValue: rawValue) var rawValue: RawValue { get } static var flowers: ShirtPattern { get } static var plaid: ShirtPattern { get } static var squares: ShirtPattern { get } static var dots: ShirtPattern { get } static var lines: ShirtPattern { get } }
47. struct ShirtPattern { typealias RawValue = String init(_ rawValue: RawValue) init(rawValue: rawValue) var rawValue: RawValue { get } static var flowers: ShirtPattern { get } static var plaid: ShirtPattern { get } static var squares: ShirtPattern { get } static var dots: ShirtPattern { get } static var lines: ShirtPattern { get } } extension ShirtPattern { static var bubbles: ShirtPattern { // generate custom pattern } }
48. Refining for Swift
49. - (nullable Document)getDocumentWithId:(NSString *)id; func getDocument(with: String) -> Document?
50. - (nullable Document)getDocumentWithId:(NSString *)id NS func getDocument(withId: String) -> Document?
51. Demo!
52. Don’t do it just because you can. Final thoughts…
53. Don't use Swift if… • You're shipping a binary framework. • You need to interact with C++.
54. Don't use Objective-C if… • You don't like Objective-C…
55. If you need to mix the two… • Think about your use case • Use the tools a your disposal, see how open source projects manage this • Think seriously about starting with Objective-C, then adding Swift • Consider that Objective-C is more compatible with Swift than Swift is with Objective-C. • Organize your project neatly!
56. oscar@swanros.com @swanros swanros.com Thanks! http://bit.ly/ioscdmx