[vampirical]

The article does mention Apple normally provides at least 3-4 days of Golden Master availability and usually a week+ before General Availability and that this is useful for various reasons. A lot of these are ecosystem failing that developers work around normally, when given enough time. Since it doesn’t seem to provide enough detail maybe I can fill in some missing context.

The App Store submission process is tightly integrated with the Xcode version used to build the app, if you want to be ready before users upgrade the App Store needs to be updated at least a few days before users automatically get the update. The App Store being updated to allow builds from the new version of Xcode is the most important issue. That only happened after 2pm ET on the 15th, and I’ve seen report their had been some delay (thankfully I only had to verify existing builds and didn’t need to submit a new build today). This means even if you had your build completely done based on pre Golden Master beta, and can either quickly reverify it or are comfortable just throwing it out there, you could only actually submit it today. Review times even without back and forth over policy points can take multiple days. Things will be worse for users over the next couple days.

iOS betas are frequently quite noisy and variable, if you test against an early beta you will need to retest against the actual GM with potential backwards compatible breaks each time. If you are either unlikely to have bugs or have enough capacity to spike doing a lot of work within a week you have the option of only doing the expensive thorough verification work against a single release.

There are still many reasons why real device testing with the production IAP environment are necessary. This is mostly a failure on Apple’s part to ever update their test environment’s capabilities and achieve parity with production. Doing this early requires you to be able to afford and have extra hardware of spend extra time having to upgrade and downgrade OS versions in order to verify the new version and continue to support live production hot fixes and support. A week between GM and GA is in the Goldilocks zone for developers, so that if they’re not doing a huge release to correspond with the iOS version they can upgrade test devices once, do one chunk of testing and fixing issues, and have their own build which will happily support both the old and new OS reviewer and live before users actually get the new OS.