The Great Swift Migration

Migrating 30,000 lines of code from Objective-C to Swift

Transcript

1. The Great Swift Migration 1
2. Self Intro 2
3. — Name: Josh Kaplan — Company: GMO Pepabo — App: minne — Strengths: English — Hobbies: Collecting Xcode versions 3
4. 30,000 lines of Obj-C 4
5. Why? 5
6. — Future proofing — Safety — Productivity with features like generics, etc — Security 6
7. How? 7
8. Modernize Objective-C 8
9. @property (nonatomic, nonnull) NSArray<MICreator *> *creators; @property (nonatomic, nonnull) MICartPayment *payment; @property (nonatomic, nonnull) MIAPIClient *client; @property (nonatomic, nullable) MICoupon *coupon; 9
10. Check nullability in current Swift code let num: Int? = nil "\(num)" // String interpolation produces a debug description for an optional value 10
11. Choosing which areas to migrate — First, modernize models — Then, ViewControllers and ViewModels/Presenters — Work on feature/module basis — Avoid converting code that is then used in obj-c — Cells and smaller views can wait 11
12. Details 12
13. Steps 13
14. 1. Move properties in m file to header and add annotations 2. Make Swift file and make extension 3. Migrate non-lifecyle methods and commit for each method 4. Make temporary method for lifecycle and IBAction method contents 5. Migrate lifecycle methods and properties 6. Update storyboard 14
15. Points 15
16. — Only minor refactoring — Writing tests first helps — Communicate with team to prevent conflicts — Things like major renaming should be in separate PRs to make review easier — Set goals and monitor progress with tools like tokei 16
17. Bonus: Migrating to SwiftUI 17
18. — Small components — Use Xcode Preview now — Fewer dependencies — Swift ! 18