Snapp Technology
Hi folks,
This week brought us a new version of Swift Playground app and a Release Candidate version of Xcode 26.4. Apple also held a fantastic online session on Foundation Models, which is a clear improvement over their previous code-along sessions. They are really listening to user feedback!
In this issue, we have a mixed bag of topics, from on-device performance tracing to avoiding some common pitfalls while building user interfaces with SwiftUI. We look at some lessons learned while using agentic development in multiple projects, peek at OpenClaw’s architecture, look at how to handle Swift Packages localization and more.
Hope you enjoy this issue.
Articles
AI/ML
Agentic Development: Multi-Project Challenges
Antoine van der Lee shares best practices for running multiple AI-assisted coding projects. Highlights from the article: avoid context switching across unrelated domains; don’t jump on every quick fix; protect your most important goals; optimize your environment with custom Agent Skills and MCPs; always plan with agents and use a “Plan, Build, Review, Compound” workflow to compound learnings into AGENTS.md files.
Tracking token usage in Foundation Models
Although it uses a 30B-parameter language model, FoundationModels’ 4,096-token context window can be difficult to manage effectively. Up until iOS 26.4, we had no proactive way to manage it, only react to errors when the context limit is reached. The new beta introduces APIs for measuring instructions, prompts, and full transcripts. The author provides a helper extension to calculate usage as a percentage of context size and links to a GitHub example.
Data
How to rename properties without losing data
Our find of the week: we did not know that in order to auto-migrate renamed properties via lightweight migration using SwiftData, you must annotate your new properties with @Attribute(originalName: "oldName"). Without it, old and new properties are treated as separate schema elements and data is lost. A great tip from Paul!
Profiling
Performance Trace Without Xcode
This LinkedIn post reveals a hidden iOS developer feature: you can measure battery drain and record performance traces directly on an iPhone without a Mac. Commenters praised it as a major time-saver for real-world performance testing.
Software Architecture
Mastering the FOSMVVM SwiftUI View Generator: A Deep Dive into OpenClaw’s Architecture
This article explores OpenClaw’s FOSMVVM architecture skill. The central principle here is that views should be thin, declarative layers bound to ViewModels via the ViewModelView protocol. The Skill introduces a generator to automate scaffolding for both display-only and interactive views, handlers for composing child views, form validation, debug support, and streamlining SwiftUI previews. It’s certainly an interesting take.
UI / UX
A Practical Guide to SwiftUI Gestures, From Tap to Composed Interactions
A comprehensive tutorial on SwiftUI gesture handling. Tt covers a wide range of material, from basic gestures (TapGesture, LongPressGesture) to composing multiple gestures for complex interactions. The included code examples demonstrate how to chain, sequence, and combine gesture recognizers to make our apps easier to interact with.
The SwiftUI Mindset: 5 Key Ideas to Avoid Common Pitfalls
This talk focuses on five key principles, going through practical examples that show common patterns and anti-patterns of building user interfaces with SwiftUI. It helps explain why certain approaches are preferred over others, and shows how to make code more predictable, performant, and maintainable by working with the framework, not against it.
Tools
📸 SnapshotTesting
The Point-Free SnapshotTesting library enables snapshot testing for any value on any Swift platform, not just UIViews, and integrates well with SwiftTesting. It supports images, text, JSON, plist, and custom diffable formats. The first run auto-records a reference; subsequent runs compare against it.