What a dSYM file is
A dSYM (debug symbols) is the companion file Xcode produces when it compiles your app. The binary you ship is usually stripped: function names, type names, source paths, and line numbers are not inside the IPA. Those live in the dSYM from the same build. Crash products (Bugly, Firebase Crashlytics, Sentry) and local tools such as atos use that file to turn addresses in a crash stack back into names. Without a matching dSYM, production crashes are only addresses.
Restore dSYM in the tool’s run settings
Obfuscation renames types, fields, and functions. If the store gets the obfuscated binary while your crash pipeline still uses the original project’s dSYM, stacks will not match. If you never restore, the log itself shows obfuscated names, which is hard to debug.
In Crab’s run settings, turn on Restore dSYM file. The tool then writes a dSYM that maps obfuscated symbols back to the original names for that run. The App Store and users still receive the obfuscated binary. You keep the restored dSYM and feed it to the crash pipeline you already use, so stacks show original symbols again. Archive the dSYM from the same Crab run as the IPA, keyed by build number. Do not put the restorable dSYM inside the IPA you submit.
Code expansion: stacks restore, line numbers do not
This limit matters. Language obfuscation can expand source: extra code is inserted, function bodies grow, and instruction addresses shift relative to the original file. After you restore the dSYM, function and type names on the crash stack still map back to original symbols, so you can tell which method crashed. Because expansion changed the instruction layout, the tool cannot correctly locate the original source line. Debug by function and surrounding context. Do not expect the line number to match the un-obfuscated file in Xcode.
If stacks are still wrong, first confirm UUID with dwarfdump -u on both the binary and the dSYM. Flutter and Unity ship extra native images; restore each one, not only the main executable. See the crash-log item on FAQ. Operator docs: crab-ios.com/docs/site.
Request a trial, then archive and submit
Download App Center, choose the General or Uni-app edition, then apply for a license on the registration-code page. The docs cover the operator steps.