https://young027.com/blog/ Notes by Zixi Yang on iOS engineering, architecture, performance, and building products. en Sun, 23 Aug 2026 00:00:00 GMT https://young027.com/blog/2b2456a1/ https://young027.com/blog/2b2456a1/ Tue, 10 Nov 2020 00:00:00 GMT Zixi Yang Designing a sync-publish share SDK between two apps, and what passing an identifier instead of a file taught me about working across teams Swift PhotoKit Architecture https://young027.com/blog/09db3ee0/ https://young027.com/blog/09db3ee0/ Tue, 16 Jun 2020 00:00:00 GMT Zixi Yang Wrapping per-target branding differences behind a Swift 5.1 property wrapper so business code stops reading build configuration Swift Architecture https://young027.com/blog/4939586e/ https://young027.com/blog/4939586e/ Mon, 10 Feb 2020 00:00:00 GMT Zixi Yang How we treated the JavaScript bridge as a protocol boundary between an iOS SDK and a real-time document engine Swift WebKit Architecture https://young027.com/blog/228847f0/ https://young027.com/blog/228847f0/ Mon, 20 Jan 2020 00:00:00 GMT Zixi Yang Why a Document SDK adopted Swinject: assemblies for module ownership, scopes that follow account and document lifetimes, and offline as a composition. Swift Dependency Injection Architecture https://young027.com/blog/242a6725/ https://young027.com/blog/242a6725/ Thu, 02 Jan 2020 00:00:00 GMT Zixi Yang A reflection on moving a complex document feed back to native UIKit after iOS 13 introduced diffable data sources and compositional layout Swift UIKit Architecture https://young027.com/blog/4b4dc9e9/ https://young027.com/blog/4b4dc9e9/ Tue, 01 Oct 2019 00:00:00 GMT Zixi Yang How ReSwift and unidirectional data flow gave a document feed one authoritative state for filtering, metadata updates, caching, and networking. Swift State Management Architecture https://young027.com/blog/ea757f4b/ https://young027.com/blog/ea757f4b/ Tue, 06 Aug 2019 00:00:00 GMT Zixi Yang Coordinating gesture handoff in a nested table view and prioritizing three competing data loads on a banner-plus-content page Swift UIKit https://young027.com/blog/57c0fc5b/ https://young027.com/blog/57c0fc5b/ Fri, 02 Aug 2019 00:00:00 GMT Zixi Yang Modeling read, edit, and link sharing as composable Swift OptionSet capabilities, resolved from grants, folder inheritance, denials, and account policy. Swift Architecture https://young027.com/blog/53774d2d/ https://young027.com/blog/53774d2d/ Thu, 21 Mar 2019 00:00:00 GMT Zixi Yang How least-recently-used eviction works, why it needs a doubly linked list plus a hash map, and a complete C++ LRU cache built on std::list. Algorithms https://young027.com/blog/df7486d3/ https://young027.com/blog/df7486d3/ Tue, 19 Mar 2019 00:00:00 GMT Zixi Yang Following one GET request through AFNetworking 3.2.1, from request serialization to per-task delegates, and how to design a networking layer around it. Objective-C Networking Architecture https://young027.com/blog/67f1730e/ https://young027.com/blog/67f1730e/ Sun, 20 Jan 2019 00:00:00 GMT Zixi Yang How Objective-C categories attach methods at runtime and rely on associated objects for storage, while class extensions compile into the class itself. Objective-C Runtime https://young027.com/blog/1898b14b/ https://young027.com/blog/1898b14b/ Sat, 20 Oct 2018 00:00:00 GMT Zixi Yang Deriving the reuse pool from first principles, then implementing a minimal one in sixty lines of Swift Swift UIKit https://young027.com/blog/0b13af02/ https://young027.com/blog/0b13af02/ Fri, 05 Oct 2018 00:00:00 GMT Zixi Yang How Objective-C message sending works: isa, classes and metaclasses, selectors, IMPs, method caches, and the three stages of message forwarding. Objective-C Runtime