Apple Developer Weekly #239 iOS 26 Beta 4
And Public Beta Too
From 13
Got super busy over the weekend and Monday, so the newsletter is a bit late this week.
By the way, can you tell which parts of this newsletter were written by Claude?
13 on July 29, 2025
🧪Apple Releases
iOS 26 beta 4 (23A5297i) Also the first Public Beta
TN3179: Understanding local network privacy Updated with clarifications for 2 bugs (rare to see bug descriptions in Tech Notes)
TN3120: Expected use cases for Network Extension packet tunnel providers Updated content related to URL filters mechanism
🤖Major Updates and Issues with Foundation Models in Beta 4
Apple engineer Julian Schiavo shared important updates on Foundation Models: Starting from beta 4, GenerationSchema supports Codable and provides JSON Schema for @Generable model parameters. This means you can now use @Generable models with any LLM (like ChatGPT), not just Apple Foundation Models - a significant advance in interoperability.
We can see extensive bug fixes in the Release Notes, showing Apple's significant investment in Foundation Models.
However, on the other hand, Beta 4 also has major known issues. The Release Notes mention:
Some instructions and prompts to the model might not lead to expected responses. (152318091)
Tool calling might not function properly if primitive types such as Int, String, or Bool are used as the argument. (152318534)
These issues make some basic operations unusable in the current version. Renowned developer Natasha the Robot expressed frustration.
While I haven't deeply studied the Foundation Models framework yet, it's clear this framework is tied to system versions, unlike third-party AI models where you can freely choose versions. This leaves developers having to choose between downgrading to Beta 3 or waiting for the next fixed version to continue development. And this wait, following the beta release cycle, will be at least 2 weeks.
What I want to say is that it's clear Apple is working very hard on Foundation Models. It's just that expectations for Apple Intelligence from developers are already low, and developers willing to invest in research are all strong early supporters. I hope these development experience shortcomings can be minimized as much as possible.
⌚️Apple Watch Apps Will Require New watchOS 26 SDK
Starting April 2026, Apple Watch apps need to support 64-bit binaries, so they must be compiled using the watchOS 26 SDK.
Most Watch apps are bundled with iOS apps, and the corresponding iOS apps also need to use the version 26 SDK. In other words, developers working on Watch apps need to start using Xcode 26 before the above date.
However, previous years have also required using the latest Xcode version for uploads starting in April, so this doesn't disrupt the annual rhythm.
👀Xcode 26 Beta 4 Adds "Show View Hierarchy" Feature in SwiftUI Instruments
Xcode 26 Beta 4 added a useful "Show View Hierarchy" button in the SwiftUI instrument. Developers can now see view updates in the view hierarchy and understand where things are happening.
👶Apple Updates Age Rating System and Requires Developer Response
Apple sent emails to all developers announcing updates to the age rating system for apps and games. Important changes include:
New 13+, 16+, 18+ ratings (previously only 4+ and 9+)
New mandatory questions covering in-app controls, features, medical health themes, violent themes
Developers must complete responses by January 31, 2026
💰IAP Retention Messaging API
Apple launched the IAP Retention Messaging Web API.
You can refer to IAP backend service RevenueCat's explanation. The main purpose is to enhance retention for subscription cancellations.
🎨Apple Launches Custom Apple Logo Wallpaper Website
Apple launched an official website allowing users to customize Apple logo wallpapers. Users can choose wallpaper styles, customize designs, and download their creations. The website's tagline is "Pick a wallpaper. Make it your own. Download your design."
Hoping for more patterns.
❓NSHipster New Article: Uncertain⟨T⟩
This is brilliant - implementing probabilistic uncertainty using Swift generics. Once again, Mattt's article has impressed me.
🤖Peter Pan: Developing Apps Using ChatGPT Agent That Operates Computers Like a Human
Peter Pan shares practical experience and tips on using ChatGPT agent that can operate computers like humans to develop apps.
Worth mentioning, iPlayground just open-sourced their session data, and Peter Pan used this data to experiment with directly creating an app. I think this is an excellent example of community interaction.
🎮Paul Hudson's Capture the Flag App
Hacking with Swift author Paul Hudson released what looks like a super fun Capture the Flag app. Completely made with SwiftUI, but the interface is highly customized like a game.
🌐Swift Erlang Actor System: Bringing Swift into Distributed Erlang Clusters
Developer carsonkatri shared an exciting new project on the Swift forums: swift-erlang-actor-system. This actor system allows Swift programs to join distributed Erlang clusters, bringing interoperability with the Erlang/OTP ecosystem to Swift's distributed actors.
To be honest, I have no idea what this does or how to use it, but it looks impressive.
📺My iOS Live Coding: iPlayground App Development Livestream and Recordings
Last week I started livestreaming iPlayground App development, probably my first time live coding on YouTube. I'm grateful that iPlayground always gives me opportunities to try new promotional tools (both the weak self podcast and the newsletter you're reading now originated from promoting iPlayground).
Currently accumulated 3 videos documenting the development (and crashes) process. Introducing development plans, environment and data preparation, getting started with AI tools. Overall development progress has just begun, interested friends are welcome to subscribe to my YouTube channel.
➕iOS Developer+ Recent Content Updates
I've been continuously writing for the iOS Developer+ paid column. Here are some recent articles. Welcome to subscribe and support.
🧠I Treat AI as Human to Reduce Cognitive and Learning Burden Treating AI tools as humans can reduce cognitive and learning burden. Sharing how I use intuition and management experience from human interaction to more effectively use AI tools.
↖️Last Issue Highlights
If you've been too busy to read last week's content, here are the highlights:
📢iPlayground 2025 Agenda and Speakers Officially Announced Taiwan's largest iOS developer conference complete agenda revealed
🎮Cyberpunk 2077: Ultimate Edition Mac Native Version Launched Important milestone for Apple Silicon Mac gaming platform
🏷️App Store Connect Adds App Tags Feature Helping users better understand app features
That's all for this week's Apple Developer Weekly. Feel free to like❤️, comment💬, or reply✉️ to share your thoughts.
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