Your AI Agent Has Amnesia: Context Rot Is Why It Forgets Your Swift Codebase by Lunch
Context rot is the reason your coding agent starts brilliant and turns into a confidently-wrong intern two hours later. Chroma's study measured it across 18 models, it hits SwiftUI codebases hard, and the fix isn't a bigger context window — it's context engineering. Here's what actually works in Xcode 26.
Build Time Optimization for the Solo iOS Developer Running 5+ Apps
Day 30 of the 30-day iOS series. Real numbers, real DerivedData chaos, and the three things that actually move the needle on Xcode build times when you're maintaining multiple apps on one machine.
Modular Architecture With SPM: When to Split (And When to Absolutely Not)
Day 18 of the 30-day iOS series, opening Week 4 on architecture. Modularization with Swift Package Manager has a real cost in build time, package graph complexity, and maintenance overhead. I show the threshold rule I use across five apps — below which you don't split, above which you must — with a real Package.swift example from BrewLog and a pure Swift Testing suite that proves the point.
A StoreKit 2 Paywall From Scratch: Subscriptions, a Transaction Listener, and a Restore Button That Works
Day 15 of the 30-day iOS series, first of a three-part run on monetization. I built BrewLog's real paywall with StoreKit 2 — two subscription products, a transaction listener, and a restore flow — with zero third-party SDKs. Every number the paywall shows comes from one pure, tested function.
SwiftData Two Years Later: What's Solid, What Still Bites, and the Migration Test You're Not Writing
Day 14 of the 30-day iOS series. SwiftData is about two years old now, and the honest verdict is mixed. I already wrote the long field report on where it broke in production — this post is the part that report didn't have room for: a VersionedSchema + SchemaMigrationPlan test that proves a schema change is safe BEFORE TestFlight finds out for you.
@Observable vs ObservableObject: What 1,000 Rows and a Redraw Counter Actually Showed Me
Day 13 of the 30-day iOS series. I built a redraw counter into BrewLog, put 1,000 rows in two identical lists side by side — one backed by @Observable, one by ObservableObject — and toggled a single favorite ten times. The row counts tied 10-10. The list counts didn't. Here's the real number, and exactly where it comes from.
@State, @Bindable, @Environment: The Complete Map for @Observable (and the Question You're Actually Asking)
Day 12 of the 30-day iOS series. With @Observable, SwiftUI lets you slap @State, @Bindable, @Environment, or a plain let on the same class — and compiles all of them. Here's the question that actually decides which one is correct, one map that resolves 95% of the confusion, and three real BrewLog bugs (one silent, one a compile error, one a runtime crash) that come from picking wrong.
ObservableObject → @Observable: The Migration Guide That Skips the Marketing (and the Autoclosure Gotcha Apple Forgot to Mention)
Day 11 of the 30-day iOS series. Apple's migration guide makes ObservableObject → @Observable look like a find-and-replace. It mostly is — except for one quiet behavioral change: @StateObject only ran your initializer once, and @State runs it on every render. Here's the multiple-init bug that causes, why it's worst in exactly the init you were proud of, and how to fix it with a test that turns 'no side effects in init' into a hard, green invariant.
ThinkBud + Foundation Models: What I Shipped On-Device, and the Wall That Sent Me Back to the Server
Day 10 of the 30-day iOS series, the build-in-public finale of AI week. I took the on-device Foundation Models stack from Days 8 and 9 and bolted it into ThinkBud, an app I actually ship. Here's the honest field report: the bounded tasks the on-device model nailed for free and offline, the context-window wall a 100K-character textbook import smashed into, and the exact line of code where I gave up and routed to a server. Plus the one decision that's pure Swift — so it gets a real test.
@Generable: Make Apple's On-Device Model Hand You a Swift Struct, Not a String to Parse
Day 9 of the 30-day iOS series, part 2 of AI week. Yesterday Foundation Models gave us a String. Today we make it give us a typed Swift value — BrewSummary(flavor:, advice:, rating:) instead of a paragraph you regex your way through. @Generable, @Guide constraints, session.respond(to:generating:), and the sleeper-within-the-sleeper: tool calling, where the on-device model calls your own Swift code mid-answer. With the TDD seam, because typed output changes what you test.
Foundation Models: Your First On-Device AI Feature With No Backend, No API Key, No Bill
Day 8 of the 30-day iOS series, and the start of AI week. The Foundation Models framework runs a real language model entirely on the phone — free, private, offline. We build the smallest thing that works: summarize a block of text in three lines, handle the availability cases that bite in production, wire it into a real app, and put a TDD seam around the part that isn't the model. Code-along, with tests.
UIDesignRequiresCompatibility: When (and Why) Opting Out of Liquid Glass Is the Pro Move
Apple hands you one Info.plist key that freezes the old design for a full year. It's not a cop-out — for banking, enterprise, and apps caught mid-redesign, opting out of Liquid Glass is the responsible call. The exact flag, a real before/after from my own app, the deadline, and a decision matrix you can actually defend in a standup. Plus the per-screen rollout gate you should be testing instead.
Icon Composer and the New App-Icon Era: One Document Instead of Three Exported PNGs
iOS 26 wants your app icon in light, dark, clear, and tinted. The old way was three flat 1024px PNGs that quietly drifted apart. Icon Composer turns it into one layered .icon document the system relights for you. The real workflow from a single SVG to a full set — plus the one decision around icons you can actually unit-test.
Custom Liquid Glass Components: When to Leave the Defaults (and the Three Mistakes That Kill Your Frame Rate)
glassEffect(.regular, in:) with a custom shape, two glass blobs that morph into each other with glassEffectID, and the three things that turn buttery Liquid Glass into a stutter machine. Built on a real iPhone 17 Pro simulator, with the TDD seam that keeps the decision testable even though the render isn't.
Liquid Glass for an App You Already Shipped: What You Get From a Recompile vs. Five Lines of Tuning
I rebuilt a real SwiftUI app against the iOS 26 SDK and took two screenshots of the exact same screen — one with zero code changes, one with five lines of glassEffect. Here's the honest split between what the recompile hands you for free and what's worth your custom-tuning time, plus the TDD seam that makes a visual feature testable.
Migrating a Real App to Swift 6.2 Strict Concurrency: 86 Errors, One Afternoon, One Race Condition I Didn't Know I Had
I migrated Invoize from Swift 6.0 strict mode to Swift 6.2 approachable concurrency on a Sunday afternoon. Every warning, every fix, the one real race condition the compiler finally surfaced — and the TDD seams I leaned on so the migration wasn't just compiler-driven guessing.
@concurrent vs nonisolated vs @MainActor: The Swift 6.2 Decision Tree That Fits on a Napkin
Four real scenarios — UI update, network call, image decode, file IO — and exactly which Swift 6.2 isolation keyword each one needs. A TDD walk-through with Swift Testing, no whiteboard ceremony required.
MainActor by Default: Why Apple Just Reversed Swift's Concurrency Story
Xcode 26 flips the default — your code now runs on the main actor unless you say otherwise. Here's why Apple changed direction, what it actually means for your existing project, and a TDD walk-through showing the migration in real Swift.
We Updated Our App Icon for iOS 26. Apple Now Wants Three of Them. So We Built a Tool.
iOS 26 Liquid Glass quietly tripled the work to ship an app icon — default, tinted, and dark variants for every iPhone app. Existing icon tools haven't caught up. We hit the wall updating ThinkBud last week, so we built a free generator. Here's what changed in iOS 26, why every iOS dev is about to learn this the hard way, and the tool we shipped to handle it.
Apple's iOS 26 SDK Deadline Hits Tomorrow. Half the App Store Isn't Ready.
April 28, 2026 — every app submitted to the App Store must be built with Xcode 26 and the iOS 26 SDK. If you haven't updated yet, your next submission gets rejected. Here's what's breaking, what you need to fix, and why this deadline is different.