Introducing LogUI: an experimental log browser

Although I often use my free log browser Ulbow daily, and it serves its purpose well, it’s time to move on with changing macOS and its APIs, and do better. Ulbow still relies on the log command tool to get its log extracts, and its front end is thoroughly AppKit.

Apple introduced the Unified log in macOS Sierra back in 2016, and at that time the only way to access it was using the log command tool, which isn’t among those for which it has provided source code. It wasn’t until Catalina in 2019 that Apple provided an API allowing developers to obtain log entries direct. As that wasn’t retro-fitted, the few apps that access the log couldn’t use that on Macs running Mojave or earlier, limiting its usefulness until relatively recently. When I developed Consolation in 2017, and its successor Ulbow two years later in 2019, I therefore continued to rely on the log command tool to obtain log extracts.

By a curious coincidence, SwiftUI was also first released for macOS in 2019, although it has taken an extraordinarily long time to approach maturity. Over the last couple of years it has improved to the point where some outstanding apps like OmniFocus have now abandoned the older AppKit API in favour of SwiftUI.

Last summer I had a first go at writing a potential replacement for Ulbow using the combination of OSLog to give direct access to log entries, and SwiftUI for its interface. At that time I reached an impasse largely as a result of excessive memory use and a memory leak that I was unable to resolve, and concluded that “Ulbow already performs better than LogUI ever could.”

More recently I have returned to that project and accepted that trying to support older versions of macOS before Sonoma is too great an impediment. Calling on some newer features in SwiftUI I have made better progress and, although not entirely continent in its use of memory, I now have an experimental version that I’m using daily. It appears robust and stable, and shouldn’t run away with all your Mac’s memory. Although it currently lacks key features like Find/Search and the ability to copy text from its browser window, it can store log extracts in rich text format.

Its Settings establish defaults common to all new browser windows:

Subsystem allows you to filter entries by a single predicate for one specified subsystem.
Period lets you set a default period for log excerpts, given in decimal seconds, so you can set 2.5 seconds if you wish.
Max entries is the limit of entries to be fetched and displayed. This can be set as high as 20,000 or even more.
Light Mode will set the app’s windows to Light Mode when you next open the app, if your Mac is also set to run in Light Mode. This allows you to opt out of Dark Mode if you really must.

Window controls let you override the first three of those defaults, and add

Start, a date and time to start the log excerpt.
Full Fields, whether to show all fields or just a shortened selection.
Get Log button to get a log excerpt.
Save as RTF button to write the log excerpt out to a rich text file.
The count of entries in the current excerpt.

The end result is, I think, a considerable improvement on Ulbow, in terms of readability, without sacrificing too much space as in Console’s rigid columns.

This experimental release comes with its own PDF documentation, also accessible within the app as its Help book. I’d be very grateful if you could take it out for a spin and see how robust its log engine is, and whether you prefer its new layout for log entries. You can download a copy from here: logui120
Note that it requires a minimum macOS version of 14.6, to ensure that it doesn’t rob your Mac of memory.

Once its engine is reliable, I will add more features, starting with Search/Find support, and the ability to copy entries from its window.

Thank you, and happy logging around.