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Show HN: I reverse engineered macOS to allow custom Lock Screen wallpapers

(cindori.com)
79 points cindori | 2 comments | 15 Sep 25 08:28 UTC | HN request time: 0s | source

Hi HN, I'm Oskar, a solo indie Mac developer from Sweden. For those in the Mac community, you might know me from my other apps like Sensei and Trim Enabler.

For years, I've been frustrated by the lack of customisation of macOS. In particular the Lock Screen which supports animated wallpapers, but only ones provided by Apple. There's never been a way to add your own personal videos.

I decided to figure out how to solve this, and the result is Backdrop 2.0. Backdrop is my Live Wallpaper app for Mac, it can play video wallpapers on your desktop. And now it can play on your Lock Screen too.

The core technical challenge, as you can imagine, came from trying to do something that Apple otherwise does not allow. However, through extensive reverse engineering of the macOS wallpaper system, I figured out a way to provide Backdrop wallpapers to the system in a way that allows them to play on the lock screen, and even appear in a custom section in System Settings.

I'm here all day to answer any questions—especially about the reverse engineering process, the challenges of integrating with macOS, or the experience of being an indie Mac developer.

Would love to hear your thoughts and feedback.

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nerdjon ◴[15 Sep 25 14:42 UTC] No.45250281[source]▶
Worth mentioning that if you want a free way to do this that does not require running additional software.

All you have to do is have a video you want to use, download one of apple's through settings, go to the location of the downloaded background (I don't remember where that is right now but a quick google search would take care of this), rename your file to the name of apple's file and then replace it.

Mac will act as if this video is the right video and use it without complaints. Until apple starts doing any checksum checks on these files I doubt this method will break anytime soon.

This has been working flawlessly for me for a while now.

This may take some finagling to make sure that your video file is not so large that your Mac can't handle it and that you are using the right format. But it is not hard to do.

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1. cindori ◴[15 Sep 25 15:19 UTC] No.45250709[source]▶
I think you will find that if you try to do that, it will actually not work properly. Visiting the lock screen repeatedly will eventually crash the wallpaper extension, producing a black screen. And updating macOS will reset all your wallpapers.

Backdrop uses a more advanced approach that ensures that it works seamlessly across reboots and macOS updates.

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2. commandersaki ◴[15 Sep 25 23:27 UTC] No.45256200[source]▶
seamlessly across reboots and macOS updates

Famous last words.