NSSpain 2023: Modularising a monolith!

Detailed image description of the sketchnote

• since 2012 LoginVC as M(assive)VC in Objective-C

Legacy Code

• no piece by piece migration possible
• no big bang change possible either

Ownership

• Alignment needed

Responsibility

1. Authentication
2. Session State

Lessons Learned

• Brainstorming & drawing diagrams helps
• A/B testing
• no major incidents

The end result

• manageable modules
• flexibility
• migrated to Swift
• ObjC 40k vs Sift 27k lines of code