Uploaded byDominique Stranz
Migrating from Objective-C to Swift
This document discusses lessons learned from migrating an application from Objective-C to Swift. It covers various challenges such as interoperability between the two languages, handling optionals and enums, and migrating Objective-C code and patterns to Swift equivalents. Recommendations are provided such as starting the migration with files without subclasses, using Swift features selectively, and adopting a file-by-file migration approach. Potential issues with architectures like MVC and patterns like delegation are also addressed.
Migrating from Objective-C to Swift
- 1. CASE STUDY: MIGRATING FROMOBJECTIVE-C TO SWIFT DOMINIQUE STRANZ
- 2. MIGRATE TO SWIFT STAYWITH OBJECTIVE-C ?
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- 4. CUI BONO? Lucius CassiusLonginus
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- 10. NO MORE HEADERFILES
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- 12. and so on, and so forth…
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- 16. Application new API Client Utils AdoptNullability Configuration Manager
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- 20. Application new API Client Utils AdoptNullability Configuration Manager
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- 22. USE „TECH DAYS” TOMIGRATE OBJECTIVE-C CODE
- 23. 34% of code in after2 months
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- 26. FILE BY FILE MIGRATION IS THE MOST EFFECTIVE WAYChild2 Base Child1 Class2 Class4 Class3
- 27. START WITH FILESWITHOUT SUBCLASSES Child2 Base Child1 Class2 Class4 Class3 YOU CANNOT SUBCLASS A SWIFT CLASS IN OBJECTIVE-C
- 28. SWIFT CLASS MUSTBE A DESCENDANT OF AN OBJECTIVE-C CLASS …TO BE ACCESSIBLE IN OBJECTIVE-C FILES Child2 Base Child1 Class4 Class3 NSObject
- 29. SWIFT CLASS MUSTBE A DESCENDANT OF AN OBJECTIVE-C CLASS Child2 Base Child1 Class4 Class3 NSObject OBJECTIVE-C WILL NOT BE ABLE TO TRANSLATE CERTAIN SWIFT-SPECIFIC FEATURES
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- 31. Mix-and-match functionality makesit easy to choose which features and functionality to implement in Swift, and which to leave in Objective-C. Interoperability makes it possible to integrate those features back into Objective-C code with no hassle. Apple Inc. “Using Swift with Cocoa and Objective-C (Swift 3).”
- 34. BUNDLE SIZE 22 MB38 MB YES FOR THE WATCHOS APP NO FOR THE WATCHOS APP EXTENSION Always Embed Swift Standard Libraries ⌚
- 35. CODE AUTOCOMPLETION FIXED INXCODE 8.3
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- 37. IN OBJECTIVE-C HEADER FILESONLY USE FORWARD DECLARATIONS NSObject @class ClassName; @protocol ProtocolName; IMPORTING A SWIFT HEADER FILE THERE WILL LEAVE YOU WITH A CIRCULAR REFERENCE.
- 38. IF BOTH SWIFTAND OBJECTIVE-C CLASSES ARE IN THE SAME APPLICATION PROJECT NSObject #import "ModuleName-Swift.h"
- 39. IF BOTH SWIFTAND OBJECTIVE-C CLASSES ARE IN THE SAME COCOA POD PROJECT NSObject #import <PodName/PodName-Swift.h>
- 40. IF SWIFT FILEIS IN ANOTHER POD NSObject @import PodName;
- 41. IF SWIFT FILEIS IN ANOTHER POD NSObject @import PodName; ADD *.SWIFT FILES TO SOURCE_FILES DECLARATION IN PODSPEC FILE
- 42. SWIFT CLASS INOBJECTIVE-C
- 43. MUST BE ADESCENDANT OF AN OBJECTIVE-C CLASS WILL NOT BE VISIBLE IN OBJECTIVE-C INT?, INT!, FLOAT?, … SOME NAMES ARE ALREADY IN USE IN NSOBJECT description: String SWIFT CLASSES CANNOT BE SUBCLASSED IN OBJECTIVE-C objc_subclassing_restricted METHODS WITH NIL TERMINATION WILL BE NOT ACCESSIBLE IN SWIFT NS_REQUIRES_NIL_TERMINATION DEALLOC IS UNAVAILABLE IN SWIFT, BUT YOU CAN USE DEINIT INSTEAD dealloc != deinit
- 44. SWIFT ENUM INOBJECTIVE-C
- 45. ENUM SHOULD HAVETHE @OBJC PREFIX @objc prefix ASSOCIATED VALUES ARE NOT SUPPORTED case variant1(value: Int) IN OBJECTIVE-C ENUM CAN ONLY HAVE INTEGER TYPE @enum Name: Int
- 46. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT RawRepresentable enum for ObjectMapper? ▸ Model should provide wrapper for Obj-C code: ▸ Translation to enum: Int during mapping transformation or in runtime ▸ Computed property `isActive: Bool`, `is…: Bool`
- 47. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT API Endpoints as URLRequestConvertible enums? ▸ Create a proxy class (inherited from NSObject) with class requests methods, that inside will use Swift enum ▸ We decided to only define methods really used by Obj-C More about elegant API Endpoints in Alamofire https://github.com/Alamofire/Alamofire#crud--authorization
- 48. WHAT WILL NSCODER FAIL TO SEE?
- 49. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT NSCoding ▸ NSKeyedArchiver, NSKeyedUnarchiver will see only properties visible for Objective-C ▸ We can change properties type or…
- 50. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT NSCoding ▸ NSKeyedArchiver, NSKeyedUnarchiver will see only properties visible for Objective-C ▸ We can change properties type or… ▸ Use value(forUndefinedKey key: String) -> Any? and setValue(_ value: Any?, forUndefinedKey key: String) to set/get not bridged properties ▸ Example: Use enum’s rawValue as encodable value
- 51. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT NSCoding
- 52. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT Future? Swift Archival & Serialization proposal ▸ It aims to provide a solution for the archival of Swift struct and enum types ▸ It aims to provide a more type-safe solution for serializing to external formats, such as JSON and plist ▸ Read more: https://github.com/itaiferber/swift-evolution/ blob/swift-archival-serialization/proposals/XXXX-swift- archival-serialization.md
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- 54. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT enum ServiceError: Error {}
- 55. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT enum ServiceError: Error {} ▸ Error type in Obj-C code? NSError without associated values…
- 56. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT enum ServiceError: Error {} ▸ Error type in Obj-C code? NSError without associated values… ▸ CustomNSError protocol: Describes an error type that specifically provides a domain, code, and user-info dictionary More: https://github.com/apple/swift-evolution/blob/ master/proposals/0112-nserror-bridging.md
- 57. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT enum ServiceError: Error {}
- 58. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT enum ServiceError: Error {}
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- 60. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT Optional(„2000 PLN”)
- 61. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT Optional(„2000 PLN”) ▸ Swift 3.1 will actually actually raise a warning when you use an optional in string interpolation More: https://oleb.net/blog/2016/12/optionals-string- interpolation
- 62. CASE STUDY: MIGRATINGFROM OBJECTIVE-C TO SWIFT APNS token == „32bytes”
- 63. read more attech.olx.com
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