Hey there, let’s tackle your questions step by step—this is a super common pitfall when adjusting app architecture, so I’ll break it down clearly for you:

1. 安装量下滑是否与仅支持64位的变更有关？ #

Yep, that’s exactly the root cause. Here’s the breakdown:

• iPhone 4s (max iOS 9.3) uses the A5 chip, which is 32-bit.
• iPhone 5 (max iOS 10) uses the A6 chip, also 32-bit.
  If your updated app was built to only support 64-bit architectures (arm64), the App Store will completely hide this version from 32-bit devices and block any installation attempts. Even though you set the minimum iOS version to 9.1 (which these devices meet), the architecture restriction takes priority here.

2. 是否意味着旧设备无法再安装我们的应用？ #

It’s split into two cases:

• For existing users who installed your app before the 64-bit-only update: They can still download the last compatible 32-bit version from their App Store "Purchased" list—Apple automatically serves the right old version for their device.
• For new users who’ve never installed your app: They won’t be able to get your latest 64-bit version. But if you previously submitted a version that supports 32-bit, Apple will still make that older build available for them to install.

3. 如何让新版应用适配旧设备？ #

Unfortunately, Apple’s current App Store policies make this tricky:
Since 2019, all app updates must be 64-bit-only. You can no longer submit a new version that includes 32-bit support (armv7/armv7s architectures) to the App Store.

That said, here’s how you can still support those 32-bit devices:

• Keep your last 32-bit-compatible version active: Apple will continue to serve this build to 32-bit devices, even as you release 64-bit-only updates for newer hardware.
• Verify your Xcode settings to confirm the architecture change: Open your project, go to Build Settings > Architectures. If it’s set to arm64 alone, that’s why the old devices can’t install the new version.
• If you need a single build for both (public distribution isn’t possible via App Store), you’d have to use enterprise distribution for the legacy 32-bit build—but this only works for internal users, not the general public.

Just a quick note: Your minimum iOS version setting (9.1) is correct for these devices, but architecture compatibility is the real barrier here, not the OS version itself.

内容的提问来源于stack exchange，提问作者user1615898