Acorn was in Apple's WWDC 2025 keynote! How f'n rad is that?

So a little before WWDC I got a chance to fly down to Cupertino in the dead of night, to secretly adopt Acorn's UI to use the new look and feel of Apple's forthcoming Liquid Glass. NDAs were signed and I can't say much—other than it was super quick to adopt for Acorn's main canvas window. Acorn is a mostly Objective-C app¹ with a codebase that's effectively 20 years old now, so that speaks to how relatively smooth this transition should be.

I was super stoked to be able to do it, and though I'm sure there will be the usual bumps along the way (especially for iOS devs), it's great to have a new UI playground to run around in.

You can watch Acorn's 15 seconds on the big screen with this timestamped YouTube link: Apple's WWDC 2025.

¹ As John Gruber pointed out during The Talk Show Live From WWDC 2025, which you should also watch.

Mark Alldritt: Script Debugger Retired:

The day has finally come. After 30 years of continuous development, Script Debugger has been retired and will no longer be available for sale. Please see this post for more information.

I just looked up when I made my first purchase of Script Debugger — version 4.5 in 2009 for $199, and it was worth every penny.

I still use Script Debugger to this day.

30 years of development is a long time, and Script Debugger is such a great app. Congrats Mark - you made something awesome.

Brent Simmons: My Wildly Incorrect Bias About Corporate Engineers

Before I went to work for Audible (five years ago now — time flies!) I had a bias about engineers that worked for large corporations. I assumed that they weren’t as good as indies and engineers at small companies, or else they’d actually be indies or work at small shops like Omni.

…

And so I learned very quickly when I started at Audible that I was very wrong. I was impressed, and grew more impressed as time went on, by my fellow engineers’ rigor, talent, professionalism, care, and, especially, ability to work with other people toward common goals.

Not long after Brent joined Audible, I clearly remember him telling me that there were really smart people there who were amazing coders. And he was completely shocked by this. The look on Brent's face was just pure amazement, and he was so happy about it!

I laughed and laughed at him. Of course there's talented people there! Only crazy people are willing to put up with having to file business taxes, mess with social security, find healthcare, deal with all the stuff you have to handle to be indie. And you don't even have to be a particularly good programmer. You just have to be persistent.

Sometimes I really miss working with other folks, so I'm especially happy for Brent that his exit to retirement was working with a great group of people, in a giant ass company. Everyone should experience that at least once.

And now Brent is retiring! I've known this for a while as well, because he's insanely excited and absolutely won't shut up about it (in a good way). I bet he's even counting down the number of meetings he has left at this point.

Pure freedom to work on what you want, for the rest of your life. And of course he's going to be coding, because Brent is a developer, and I don't think you could stop him anyway.

Congrats, Brent.

Christian Ekrem: Coding as Craft: Going Back to the Old Gym:

But the core of programming – the thinking, the designing, the architectural decisions – these are the parts I want to preserve as my craft. These are the muscles I want to keep strong by training in the old gym.

…

Just as a chef might use a food processor for tedious prep work but would never dream of automating the creative aspects of recipe development and flavor balancing, we should use AI for what it’s good at while preserving the parts of coding that bring us joy and growth.

I love using AI tools to help me figure out things or to brainstorm, but it's the little highs I get when I solve a good problem that I don't ever want to go away.

From The Verge earlier this week:

During Meta’s antitrust trial today, lawyers representing Apple, Google, and Snap each expressed irritation with Meta over the slides it presented on Monday that The Verge found to contain easy-to-remove redactions. Attorneys for both Apple and Snap called the errors “egregious,” with Apple’s representative indicating that it may not be able to trust Meta with its internal information in the future. Google’s attorney also blamed Meta for jeopardizing the search giant’s data with the mistake.

Presumably, the folks from Meta used a PDF editor to draw a black vector box around the sections to be redacted. The problem with this technique is that you can open up that same PDF in an editor and delete the box to see what’s underneath.

The correct solution would have been to rasterize the PDF (which is the process of turning vectors to pixels), so any attempt to remove the redacting box would reveal an empty area. When you rasterize a page, you’re essentially baking the PDF.

As John Gruber notes:

You can properly redact a PDF digitally, but botched digital redactions are so commonplace (and at times disastrous and/or humiliating) that when then Attorney General William Barr released the Mueller Report in 2019, the DOJ printed the unredacted original, did the redactions on paper, and then scanned it back in to create the redacted PDF.

But there’s an easier way: use Retrobatch of course!

The workflow would look something like this:

You read the PDF, split the pages up, add a matte background to each page which also happens to rasterize it as well, paste the pages back together with the PDF Maker node, and then write the PDF back out.

You can also control the resolution of the rasterization by using the “Set DPI” node before the page splitter.

I think there’s enough specialized PDF tasks that need to be done that I should probably make whole PDF category in Retrobatch, including a standard PDF rasterization node.

Gabriel Nicholas at Wired: The Subjective Charms of Objective-C

But the longer I spent writing Objective-C, the more I felt it hid rather than revealed. Long, sentence-like function names buried the most pertinent information under a fog of dependent clauses. Small features required long-winded pull requests, making it easy for engineers to get distracted during reviews and to miss bugs. Objective-C’s excess words, multiplied across thousands of files and millions of lines of code, made for an exhausting codebase.

My own experience with Objective-C has been very different. I wonder if that’s because I work as a solo developer, and the architecture of my apps has always been stable? I always found the early mantra “If it feels hard, you’re probably doing it wrong” when working with AppKit and Objective-C to be more true than not.

Anytime I hit a stumbling block something like “The Way of the Code Samurai” from Wil Shipley would play through my head. Were people who disliked Objective-C fighting it rather than flowing with it?

To me, Objective-C has always felt expressive and capable, doubly so when I first started using it. After coding in Java for years I felt like I could fly.

Swift is the thing now, and both Acorn and Retrobatch use it for parts. But Swift is a heavy and unsettled language, not to mention extremely slow to compile.

I hope someday we’ll get a version of Swift that isn’t chasing whatever the hot new coding paradigm currently is, and isn’t weighed down by ever expanding complexity. I think that could be pretty nice.

Chris Lattner, the creator of Swift, in an interview:

“Swift, the original idea was factor complexity (…) massively failed, in my opinion (…) Swift has turned into a gigantic, super complicated bag of special cases, special syntax, special stuff”

I wonder, what comes after Swift?

Alex Harri: A Flowing WebGL Gradient, Deconstructed:

This effect is written in a WebGL shader using noise functions and some clever math.

In this post, I’ll break it down step by step. You need no prior knowledge of WebGL or shaders — we’ll start by building a mental model for writing shaders and then recreate the effect from scratch.

This was an absolutely wonderful read on constructing a nice looking animated WebGL shader, from the very basics up to the end product.

New to me in this post was the concept of stacking sine waves — what a clever idea.

You might remember Harri’s post “The Engineering behind Figma’s Vector Networks” from back in 2019.

Geoffrey Litt: Stevens: a hackable AI assistant using a single SQLite table and a handful of cron jobs

The assistant is called Stevens, named after the butler in the great Ishiguro novel Remains of the Day. Every morning it sends a brief to me and my wife via Telegram, including our calendar schedules for the day, a preview of the weather forecast, any postal mail or packages we’re expected to receive, and any reminders we’ve asked it to keep track of. All written up nice and formally, just like you’d expect from a proper butler.

SQLite, cron, and open APIs. This is the type of hacking that I really dig and I've considered putting together as well.

This passage from the end really resonated with me:

I’ve written before about how the endgame for AI-driven personal software isn’t more app silos, it’s small tools operating on a shared pool of context about our lives.

I keep on coming back to the idea that I need to gather more data about myself and store it somewhere easily accessible by custom AI tools. I write a little bit of stuff in Day One, but I keep meaning to build something on top of SQLite as well. Of course, I also keep on hoping Apple would do the same, but they'd probably move too slow to make it interesting.

If only I could clone myself. I have a ton of ideas but not enough time to implement them all. Such is the beauty of life i guess.

With the release of Acorn 8 last December, I published "ACTN002 Acorn's Native File Format" as part of the documentation updates, which is exactly what it sounds like.

Without going into details (that's what the technote is for), Acorn's file format is a SQLite database, with a simple three-table schema, containing TIFF or PNG bitmaps to represent bitmap layers, and a plist to represent shape layers. Acorn has kept this simple format since version 2.0 back in 2009.

And since the format is a SQLite database, it is incredibly easy for a programmer or anyone else who isn't afraid of Terminal.app to get a composite out of an Acorn file:

echo "select writefile('/tmp/pizza.png', value) from image_attributes where name = 'composite'" | sqlite3 pizza.acorn

That's it. You've now got a PNG copy of the Acorn file "pizza.acorn" written to /tmp/pizza.png.

SQLite is bundled with pretty much everything these days, which means you can write some code in Python, Swift, Objective-C, whatever, and easily support reading Acorn files. Here's an incredibly short Python script to do that:

import sqlite3
import sys

conn = sqlite3.connect(sys.argv[1])
cursor = conn.cursor()

cursor.execute("select value from image_attributes where name = 'composite'")
result = cursor.fetchone()

with open(sys.argv[2], "wb") as f:
    f.write(result[0])

Note: you should really perform some error checking in actual Python code.

What about in Swift? That's easy too.

This file format has worked well in Acorn for 16 years now, and I plan on keeping it the same moving forward.

Last week I bought a 13" MacBook Air in Midnight (24GB memory, 512GB SSD).

I hadn't been planning on buying it. Instead, I was expecting to upgrade my current desktop (M1 Ultra) to an M4 Ultra later this year. Assuming, of course, that we would see an M4 Ultra later this year. But as we know, that didn't happen. (Maybe we still will*?)

At any rate. This machine. A 13" Midnight MacBook Air.

It's beautiful. Have you seen it yet?

I ended up buying one because it's cheap, and I haven't had a travel laptop in a while. This new laptop could also double as a new build server to replace my M1 Mac mini, and I figured someday I'll hand it down to my daughter.

The size is perfect for what I'm after. I can use my 13" iPad Pro as a second display, with the bonus that I've now got instant stylus support in Acorn because of that.

And it's so amazingly fast.

I wasn't expecting that last part. So fast.

Its name is Jimi by the way.

What I'm personally interested in is, how fast can Jimi build Acorn (~200k lines of code). Sure, the single-threaded performance of the M4 processor will certainly beat my M1 Ultra (named "SRV"), but the Ultra has so much more RAM and CPU cores. How close will the Air match the performance of my desktop?

With a full build of Acorn, including running hundreds of regression tests, Jimi outperforms my M1 Ultra at 3m21s vs 4m43s. And when purely compiling Acorn, where you'd think the Ultra would have an edge, I get 1:36 (Air) vs 2:05 (Ultra).

I'm sorry, what?

This $1400 machine is beating my $4000 desktop machine with a 20 core CPU, 48 core GPU, and 64GB of memory? What why how?

So I'm pretty happy with this dinky little travel / build machine. It's a joy to hold and fun to use.

There's been a lot flying around the social web the past couple of days about Apple completely botching their AI push, and I haven't seen a whole lot of solutions (I fully admit I could completely be missing it). But off the top of my head, here's one idea that I think could really help and reap benefits for both Apple and developers.

Build a semantic index (SI), and allow apps to access it via permissions given similar to what we do for Address Book or Photos.

Maybe even make the permissions to the SI a bit more fine-grained than you normally would for other personal databases. Historical GPS locations? Scraping contents of the screen over time? Indexed contents of document folder(s)? Make these options for what goes into the SI.

And of course, the same would be true for building the SI. As a user, I'd love to be able to say "sure, capture what's on the screen and scrape the text out of that, but nope - you better not track where I've been over time".

And similar to the Spotlight indexing API, developers should be able to provide data to the SI along with rich metadata. Rev the Spotlight plugin API so that it can do more, or come up with a new API.

Is this information collected for the SI going to be the most sensitive bucket of bits on your device? Yes, of course it is.

But give developers the opportunity, and then customers will have something to choose from. Make the Mac and iOS the best platform to build personalized LLMs.

Let the apps die and live based on their own merit and reputation. Apple can build the platform, and maybe expand on it over time and use it themselves.

I want to see the apps that are made outside of Cupertino. I want to see what can happen when developers have a solid foundation to build on.

As my usage of LLMs has been increasing lately, I find myself more and more frustrated with Siri, specifically on the Mac.

As a Mac user, I have this incredible wealth of GPU and CPU power, which in turn allows me to run LLMs locally.

A few weeks ago, before a trip out of the country for my daughter's spring break, I set up a local instance of DeepSeek and made sure I could connect to it via Tailscale running on my Mac.

Why did I do this? Two reasons.

The first was because I could and there's something inherently cool and fun about running these models locally. It's a joy to play around with this stuff.

The second was a tinge of paranoia. What if I wasn't able to access the models I usually use from out of the country? LLMs are so useful for so many things, I really don't want to lose access now that I know about them. Yes, I could route all requests through my VPN, but … still, what if I couldn't?

So I can run models locally on my M1 Mac, and while it's not as fast as running it on Anthropic or OpenAI's servers, it was still usable. Which is mind blowing to me. I honestly never expected to see this tech in my lifetime. (Yes, LLMs get a lot wrong, but they also get so many things right and help me out with tedious coding chores).

A week or so ago I was grousing to some friends that Apple needs to open up things on the Mac so other LLMs can step in where Siri is failing. In theory we (developers) could do this today, but I would love to see a blessed system where Apple provided APIs to other LLM providers.

Are there security concerns? Yes, of course there are, there always will be. But I would like the choice.

The crux of the issue in my mind is this: Apple has a lot of good ideas, but they don't have a monopoly on them. I would like some other folks to come in and try their ideas out. I would like things to advance at the pace of the industry, and not Apple's. Maybe with a blessed system in place, Apple could watch and see how people use LLMs and other generative models (instead of giving us Genmoji that look like something Fisher-Price would make). And maybe open up the existing Apple-only models to developers. There are locally installed image processing models that I would love to take advantage of in my apps.

I'm glad I'm not the only one thinking about this. Ben Thompson writes at the end of Apple AI’s Platform Pivot Potential:

This doesn’t necessarily preclude finally getting new Siri to work; the opportunity Apple is pursuing continues to make sense. At the same time, the implication of the company’s differentiation shifting to hardware is that the most important job for Apple’s software is to get out of the way;

This passage isn't the crux of the article, but it really resonated with me, and I hope it does with some folks inside Apple as well.

…

(Update) Manton Reese is thinking along the same lines: Apple's response to AI:

I’m not sure Apple knows what a big risk they are taking by letting OpenAI and others lap them in the AI race. It’s a risk that will pay off if they can execute. Just as likely, though, we are seeing such a disruption in computing that Apple is vulnerable for the first time in a decade.

Acorn 8.1 is out. Full release notes are available as well.

For a .1 update, there are a bunch of new features and improvements. I think I was riding on the high of a great 8.0 release and felt compelled to keep on adding cool stuff.

As already mentioned, Acorn 8.1 includes a new scrub zoom which has been a long-standing request.

Another long-standing request included in 8.1 is the ability to resize selections using on-canvas handles, or via the palette.

Autosave has also had a revamp. There are three options now: "Off", "Native Acorn Images", and "All Images". The default is set to saving native images (.acorn).

In Acorn 8.0 (and previous versions), when autosave was enabled, non-native files (.jpeg, .png) would open without a reference to the original file on disk. This is no longer the case in Acorn 8.1, where non-native files open with a reference to the original file, and pressing ⌘S will save back to the original, regardless of the autosave setting.

Why the change? I found myself wanting autosaving of files where full fidelity would always be preserved (which is what happens when you save .acorn files), but that behavior didn't always make sense when opening a .jpeg file. JPEG files are lossy, so opening and saving the image multiple times would degrade the quality of the image. That's not awesome. And you would also lose the edibility of text and layers.

To make the autosave behavior work with multiple file types took a bit of runtime dynamics, especially since I wanted everything to work seamlessly with the macOS frameworks and versions support. I eventually got there with a bit of help from Dave DeLong, which was much appreciated. I had a solution, but I don't think it was nearly as good as what Dave came up with.

There are also a handful of bug fixes and other improvements that are worth looking over the release notes for.

I've also been regularly updating the documentation, and any changes of note get mentioned in the update log of the docs.

What's next? I plan on giving Retrobatch a bit of attention. It's a fun app to work on as well, and there's always common functionality that can pass back and forth with Acorn.

Charlie Monroe: A few words about indie app business:

A while ago, someone asked me for advice about starting an indie app business. So I’d given it some thought and wrote back a few points – and I thought it would be a good idea to put it out here for anyone else who’s thinking about doing this. Let’s start from the beginning.

It's a good read and any indie developer should put it on their list.

This part made me laugh:

Or just have a complete exit strategy – I eventually plan on getting a woodworking workshop and building furniture. Depends on what floats your boat.

Sounds familiar.

via DF.

A feature that's been asked for in Acorn, for probably over a decade now, is the ability to scrub zoom. This is where you can click and drag left or right with the zoom tool selected, and your image is zoomed in or out. It's a great feature and I'm happy to say that I've recently added it for the upcoming release of Acorn 8.1. And you can try it out right now if you'd like, by downloading a preview release of Acorn 8.1 from the latest builds page.

There are two ways to toggle this behavior.

1. Via the Zoom palette: Use the “Scrub zoom” checkbox located right above the image histogram in the zoom palette (see the image to the right).

2. With a keyboard shortcut: This is for my friends who like to keep their fingers on the keyboard. You can press the ‘z’ key twice in quick succession to toggle the preference on and off.

And while I was diving into Acorn's zoom code, I cleaned up a few things and increased the maximum zoom level to 25,600%, more than double the previous limit.

And here’s a quick tip: Did you know that, in addition to pressing ⌘1 to zoom your image to 100%, you can also double-click the zoom slider handle to achieve the same effect?

You can download a preview of Acorn 8.1 from the latest builds page.

Dr. Drang and Allison Sheridan have some great tips for adding Retrobatch droplets to the Finder toolbar:

Allison Sheridan:

My main use of Retrobatch is to make featured images for blog posts that match what most if not all of the social media services will recognize. That droplet thing is money. I keep mine in the toolbar of Finder though since I always have a Finder window open when I’ve made a screenshot.

And Dr. Drang on how to do this:

So I moved the Trim Screenshot app [Retrobatch droplet] into the Applications folder and set about adding it to my Finder toolbar. I control-clicked on the Finder window’s toolbar, selected Customize Toolbar…, and dragged the Trim Screenshot icon into the toolbar, putting it to the right of the folder name. Since I keep a post’s screenshots in the same folder as the Markdown source, I always have that folder open when writing. It’s now a simple matter to drag the screenshot from the Finder window up into the toolbar and drop it on the Trim Screenshot icon.

I've been doing something similar when updating Acorn's documentation recently. I have a subfolder in my ~/Applications folder named RBDroplets, and in there I put a Retrobatch droplet, which is then added to my Finder toolbar. This particular droplet reads in an Acorn image and then spits out JPEG-XL, WebP, and JPEG versions of that file in the same directory the Acorn image is in. Then in my documentation I have a little scriptlet that looks like this:

<% pic(writer, 'preferences_images/prefs_registration', ['webp', 'jxl', 'jpeg'], width="800", alt="Registration Settings"); %>

And it creates a picture HTML tag with the correct images and using the last element in the type array as a default.

Droplets are fun, but it's annoying if you save them to the Desktop or Downloads folder, macOS flips out and throws up a warning if the contents of it change in any way, and it's no longer a "trusted" app.

(Related: if anyone knows how to turn this warning off per app / bundle id, I'd love to know how).

I've got two app updates for you today.

Acorn 8.0.1 is out, which is of course about bug fixes that made it past the final release. It always happens, but this time around it was pretty mild. Release notes are avilable.

Retrobatch 2.2.1 is also out, with some RAW image performance improvements, and a couple of new features. Release notes for Retrobatch 2.2.1 are also avialble.

MinnMax: Panic, Playdate, Infinite Independence (YouTube link).

A video mostly about everyone's favorite indie Mac company, Panic. It came out a few months ago, but I somehow completely missed it. Cabel Sasser gives a tour of Panic's new offices, shows off their McDonald’s-inspired kitchen, and shows some interesting bits from their Panic History Archive room.

Acorn 8 has been released!

This is a major update of Acorn, and is currently on a time-limited sale for $19.99. It's still a one-time purchase to use as long as you'd like, and as usual, the full release notes are available. I want to highlight some of my favorite things below.

"Select Subject", "Mask Subject", and "Remove Background" are new commands which use machine learning (or A.I. if you prefer) to find the most important parts of your image, and then perform their respective operations. This has been a request for a long time, and while I was doubtful of its utility, it's actually pretty fun to play with and more useful than I figured it would be. So I'm glad I took the time to integrate it.

You can now set your measurement units to inches, centimeter, or pixels, and it shows up across the tools for your image, not just specific ones. This includes the crop palette, shape dimensions, filter settings… well, pretty much everything. This might be the oldest feature request I've implemented so far. And then related to this, Acorn 8 now has an on canvas ruler which you can use to measure out distances, straighten your image with, or even redefine the DPI.

Look up Table (LUT) support. LUTs are pretty fun, and they work by mapping one set of colors to another, enabling consistent or stylized visual effects. LUTs are used primarily in photography or filmmaking, and you can download and install new LUTs from various places across the internet.

Acorn 8 has the ability to read in a CSV file and it'll dynamically swap in the row values and replace text or bitmap graphics depending on what's in the data file. It's like mail merge, but for images. This is pretty awesome if you have a bunch of templated images you want to create.

Acorn has a new "Quick Processor". It's a quick version of the Shape Processor, where you can duplicate shapes, rotate, transform, and apply other operations to them. You can even use snippets of JavaScript to perform your own magic to shapes, including modifying anchors in bezier shapes. I hope to build a little library of cool JavaScript shape filters for this in the future.

OK, now for some geeky implementation things.

OpenGL has been completely removed and Acorn is 100% Metal. This was nice to do, and I was waiting to drop support for older versions of macOS first, but I'm glad it's finally happened.

Acorn's Shortcuts support has been completely rewritten (in Swift) to use the new App Intents framework. Hopefully this puts Acorn in a good place for the future as Apple adds more Siri integration to apps. Maybe someday you'll be able to say "Open up these selected images in Acorn, crop them to 4x3, convert to PNG, save and close them". That's the dream anyway.

Acorn's internal Bézier implementation has been reworked. This was one of the first things I did, as there was a mismatch in the internal API that Acorn used and what it presented on screen. In the classic implementation of Bézier curves you have a start point, two control points (cp1 & cp2), and an end point. But that's not how anybody actually uses when it's presented on screen. On screen you generally manipulate a single anchor, which can represent both a start and end point, and the previous curve's cp2 and the next curve's cp1. Not to mention all the nuances where a shape can have multiple continous paths, or maybe the path is closed or it's still open. So I wrote a fun shim on top of the Bézier "data" which became the new interface for Acorn's canvas to manipulate anchors and such. I backed it all up with tests and this new model ended up fixing some bugs and making the implementation cleaner. It's always a good feeling when you can get something done like that, even if it doesn't really change anything that the customer can see.

And finally, Acorn's documentation has been converted from custom RTF files (and an app named "FMWrite") into Markdown, which hopefully opens up the door for more integration with templates and services. I certainly have been enjoying seeing diffs between revision commits.

Of course there's more. There's always more. Make sure to tell a friend, and even check out the full release notes.