Xcode 26 RC

Build Environment Mobile
18

FYI that we’ve seen the iOS 26 simulator device hang indefinitely on startup roughly ~10% of the time. We have filed a support ticket with Apple. In the meantime, here is a workaround:

  1. The boot-simulator command takes in three parameters:

    1. device (“iPhone 17 Pro”)
    2. platform (“iOS”)
    3. version (“26.0”) NOTE: this must be quoted to coerce it to a string data type in yaml

  2. Using homebrew, add the coreutils package. This installs the timeout command.

  3. Using the parameters, a device UDID is determined. if one can’t be found, the step fails

  4. The simulator is booted. If it hasn’t succeeded (the boot command returns without exit) in 60 seconds, then the simulator is force shutdown. After a brief timeout it will retry.

For this to work, any tools or frameworks that connect to simulators will need to ensure they are set up to boot the same device that this workaround starts up.

Here’s the command that can be added to a CircleCI YML config and further customized:

commands:
  boot-simulator:
    parameters:
      # i.e. "iPhone 17 Pro"
      device:
        type: string
      # i.e. "iOS"
      platform:
        type: string
      # i.e. "26.0" (ensure quoted to coerce value to string)
      version:
        type: string
    steps:
      - run:
          name: install coreutils (provides timeout utility)
          command: brew install coreutils
      - run:
          environment:
            SIM_VERSION: <<parameters.version>>
            SIM_DEVICE: <<parameters.device>>
            SIM_PLATFORM: <<parameters.platform>>
          name: Get Simulator Device UUID - <<parameters.platform>>-<<parameters.device>>
          command: |
            ESCAPED_VER=$(echo "$SIM_VERSION" | tr '.' '-')
            SIMREQ="${SIM_PLATFORM}-${ESCAPED_VER}"
            SIMLIST=$(xcrun simctl list -j)

            UDID_not_found() {
              # arguments: requested simulator, device
              SIMS=$(xcrun simctl list devices | tail -n +2)
              echo "ERROR!: UDID not found, check Platform, Version and Device"
              echo "Requested: Simulator: ${1}, Device: ${2}"
              echo "Available:"
              echo "${SIMS}"
              exit 1 
            }

            SIMREQ_not_found() {
              # arguments: requested simulator runtime
              echo "ERROR!: Simulator runtime not found"
              echo "Requested: Simulator Runtime: ${1}"
              echo "Available Runtimes:"
              echo "${SIMLIST}" | jq -r '.devices | keys[] | select(startswith("com.apple.CoreSimulator.SimRuntime."))'
              exit 1
            }

            if ! echo "${SIMLIST}" | jq -e ".devices | has(\"com.apple.CoreSimulator.SimRuntime.${SIMREQ}\")" > /dev/null; then
              SIMREQ_not_found "${SIMREQ}"
            fi

            UDID=$(echo "${SIMLIST}" | jq -r ".devices.\"com.apple.CoreSimulator.SimRuntime.${SIMREQ}\"[] | select(.name==\"${SIM_DEVICE}\").udid")

            if [[ -z "${UDID}" ]]; then
              UDID_not_found "${SIMREQ}" "${SIM_DEVICE}"
            fi

            echo "export UDID=${UDID}" >> "${BASH_ENV}"
      - run:
          name: Launch Simulator
          background: true
          command: |
            max_attempts=10
            attempt=1

            while [ $attempt -le $max_attempts ]; do
                echo "Launching Simulator (Attempt $attempt/$max_attempts)"
                
                if timeout -s SIGKILL 60s xcrun simctl bootstatus "${UDID}" -b; then
                    echo "Simulator Booted Successfully"
                    exit 0
                else
                    echo "Sim boot stalled. Powering down..."
                    xcrun simctl shutdown "${UDID}"

                    echo "Retrying in 5s..."
                    attempt=$((attempt + 1))
                    sleep 5
                fi
            done

            echo "Simulator Boot failed after $attempt attempts"
            exit 1
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