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Troubleshooting

An error about which simulator to use​

You can omit --udid only when exactly one simulator is booted. If several are booted (or none), idb-repl cannot choose and errors. Fix: boot a single simulator, or pass --udid <udid> explicitly. List targets with idb list-targets.

My code failed but the shell exit code is still 0​

idb-repl always exits 0, whether your code succeeded or failed. Do not branch on the exit code. Instead, check the prefix of the output:

  • Result: followed by the value ⇒ success.
  • Error: followed by a message ⇒ failure (e.g. a compile error).

"Expected a return" / no value printed​

Every submission must end in a return of the value to surface — in one-shot mode, and in interactive mode before each /run. For a void action (like IDB.ui.tap), add a trailing return "done".

String interpolation breaks when piping with printf​

When piping the interactive REPL via printf, escape Swift interpolation's backslash: \\(...). In one-shot mode the code is a single-quoted shell argument, so \(...) passes through with no escaping. See Examples → Two ways to run.

Piped stdin is ignored​

If you pass a trailing code argument, idb-repl runs in one-shot mode and ignores stdin. To drive the interactive REPL via printf, omit the trailing code argument.

A symbol from the app/target isn't visible​

  • In the simulator and app contexts only Foundation (and, in the default host app, UIKit) plus the IDB API are imported by default. Add an import for other modules from the iOS SDKs. You can also import Swift modules from a target app, but this feature is experimental. Objective-C classes and methods can be used dynamically. See Writing REPL code → Which context imports what.

An IDB.* command did nothing​

IDB.* calls don't throw. A command that doesn't apply is a silent no-op, and if the connection drops the submission simply stops. Check that the element/marker exists (inspect IDB.ui.describeAll()), and that the intended app is frontmost.

A screenshot/video path doesn't exist locally​

Paths returned by IDB.screenshot / IDB.video are on the same filesystem as the simulator, not necessarily your local machine — relevant when using a remote --companion. To collect artifacts locally, run with --report-path, which gathers captured files along with the report. See Reports and replay.

Wrong Swift toolchain​

Injected code compiles with the toolchain from the selected Xcode (xcode-select -p). If you need a different toolchain, pass --toolchain-path <path>.

Checking your build​

idb-repl --version prints the build date and time — useful for confirming you're on a recent build.