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Simulator detection (iOS)

SimulatorDetection.getStatus() · SimulatorDetection.isSimulator() · check id simulator

Running on a simulator is not a compromise. It is where nearly all development and much automated testing happens. This check exists so an application can tell a simulated environment from a physical one — not so it can refuse to run in one.

1. What it detects

Whether the process is running on the iOS Simulator.

2. Why it earns its own check

Two reasons beyond reporting the fact:

  1. Other checks depend on it. Jailbreak detection returns unavailable with reason simulator, and the iOS parent-process debugger heuristic returns indeterminate there. Both would otherwise produce false positives on every development run.
  2. It is genuinely reliable, which almost nothing else in this toolkit is.

3. Signal

ID Indicator Confidence
RNSEC-IOS-SIMULATOR-001 Running on the iOS Simulator high

Uses the compile-time targetEnvironment(simulator) flag, with SIMULATOR_DEVICE_NAME as a runtime cross-check for a binary built for a device but running somewhere unexpected.

4. Confidence

The compile-time flag is exact, so this signal has no indeterminate outcome — there is nothing to fail to read. That is asserted by a test, and it makes this the only check in the toolkit with no inconclusive case.

Contrast with Android emulator detection, which infers from build strings, device nodes and hardware profile against a signature list that ages, and which hardened emulator images are built to defeat. The two are not comparable in reliability, and the docs do not pretend otherwise.

5. False positives and negatives

There are no meaningful ones. A binary compiled for the simulator runs on the simulator.

The only edge worth noting: this reports the environment, not the device. A physical device attached to Xcode is still a physical device, and this check correctly says so — use debugger detection for that question.

6. Recommended application response

if (await SimulatorDetection.isSimulator()) {
  // Reasonable: skip hardware-dependent flows, use test fixtures, relax a
  // policy that would otherwise block development.
  // Unreasonable: refuse to run. This is where your developers work.
}

7. Tests

ios/EngineTests/SimulatorDetectorsTests.swift — 3 cases, including an assertion that the detector never produces an indeterminate outcome.