Starting in January 2018, all new apps submitted to the Mac App Store must include 64-bit support. Existing apps have until June 2018 to support this requirement.
On a post to its developer website today, Apple reminded developers of the coming change. Apple is also urging developers who distribute apps outside the official Mac App Store to push out 64-bit binaries so users can continue to run those products on future versions of macOS.
As the company noted in previous developer updates, macOS High Sierra is the last macOS release to support 32-bit apps “without compromise.” Apple first announced this requirement at WWDC in June.
Apple migrated its entire Mac hardware lineup to 64-bit Intel processors in 2006. The company recently completed a transition to 64-bit for iOS, just two years after kicking off the campaign. Apple’s iOS 11 no longer supports legacy 32-bit apps.