Apple’s Developer site has today shared a reminder that starting January 1st, 2018 32-bit Mac apps will no longer be accepted.
Earlier in the year we reported that iOS 11 would be the death blow to all 32-bit mobile apps and that the same would apply for Mac apps with macOS High Sierra in the future.
Starting January 1, all new apps submitted to the Mac App Store must support 64-bit architecture, while existing apps must be updated to 64-bit by June 2018. Apple recommends that if you distribute your app outside of the App Store you should update your app to run 64-bit as well. This is due to the fact that macOS High Sierra will be the last macOS release to support 32-bit architecture.
Apple also shared its support site for distributing Mac apps.
As a reminder, new apps submitted to the Mac App Store must support 64-bit starting January 2018, and Mac app updates and existing apps must support 64-bit starting June 2018. If you distribute your apps outside the Mac App Store, we highly recommend distributing 64-bit binaries to make sure your users can continue to run your apps on future versions of macOS. The last macOS release to support 32-bit apps without compromise is macOS High Sierra.