iOS本地抗卸载短字符串存储位置咨询：Keychain是否可行？

First off, your call on Keychain is 100% correct. When an iOS app is uninstalled, all app-specific Keychain items get wiped automatically by the system. Apple's sandboxing rules are strict here—every piece of data tied directly to your app, whether in the sandbox directory or Keychain, gets cleaned up to protect user privacy and free up space.

To answer your core question: There is no native local storage location on iOS that survives app uninstallation for app-specific short strings. The OS is designed to fully remove all traces of an app when a user decides to delete it, so there's no loophole here for purely local, app-only persistence.

That said, here are practical workarounds if you need to retain that short string across uninstalls/reinstalls:

• Cloud Storage (most reliable option)
  Upload the string to your own backend server, or use Apple's iCloud services like iCloud Keychain or iCloud Drive. For iCloud Keychain specifically, if users have iCloud sync enabled, the data can be retrieved when they reinstall your app (since it's tied to their Apple ID, not the app itself). Just note that users can disable iCloud sync, so this isn't guaranteed for all cases.
• App Group Shared Keychain (limited use case)
  If you have multiple apps under your developer account, you can set up an App Group and use shared Keychain entries. Uninstalling one app won't delete the shared Keychain items as long as at least one other app in the same group remains installed. But if all group apps are uninstalled, those items will still be deleted. This only works for apps you control, not as a cross-app solution.
• System-Tied Identifiers (caveats apply)
  You could leverage identifiers tied to the user's Apple ID or device, like the IDFA (but note users can reset this) or the identifier for vendors (IDFV, which resets if all apps from your vendor are uninstalled). These aren't meant for storing custom short strings though—they're for identification purposes only, and you can't save arbitrary data here.

A critical note: Any attempt to bypass iOS's sandbox rules to retain data post-uninstall will violate Apple's App Store guidelines, and there's no official API that lets you do this anyway. Stick to the above legitimate methods to avoid getting your app rejected.

内容的提问来源于stack exchange，提问作者Regis St-Gelais