How would you decide whether to refactor a legacy UIKit app into SwiftUI incrementally or rewrite it completely?

Incremental migration is preferred unless the architecture is fundamentally unmaintainable or blocking product velocity.

A full rewrite introduces high risk: feature regression, instability, and long delivery delays. Incremental adoption using UIHostingController allows coexistence of UIKit and SwiftUI. Decision depends on codebase health, team capacity, and release pressure. Staff engineers prioritize risk management over architectural purity.