Debugging on iOS/macOS

Here we describe how to debug a build using Xcode, Apple’s preferred IDE for developing for macOS and iOS.


  • Bundle the app by using bob, with the --with-symbols option (more info):

      $ cd myproject
      $ wget<sha1>/bob/bob.jar
      $ java -jar bob.jar --platform armv7-darwin build --with-symbols --variant debug --archive bundle -bo build/ios -mp <app>.mobileprovision --identity "iPhone Developer: Your Name (ID)"
  • Install the app, either with Xcode, iTunes or ios-deploy

      $ ios-deploy -b <AppName>.ipa
  • Get the .dSYM folder (i.e the debug symbols)

    • If it’s not using Native Extensions, you can download the .dSYM file from

    • If you are using a native extension, then the .dSYM folder is generated when you build with bob.jar. Only building is required (no archive or bundling):

        $ cd myproject
        $ unzip .internal/cache/arm64-ios/
        $ mv dmengine.dSYM <AppName>.dSYM
        $ mv <AppName>.dSYM/Contents/Resources/DWARF/dmengine <AppName>.dSYM/Contents/Resources/DWARF/<AppName>

Create Project

To properly debug, we need to have a project, and the source code mapped. We’re not using this project to build things, only debug.

  • Create new Xcode project, choose the Game template


  • Choose a name (e.g. debug) and the default settings

  • Choose a folder to save the project into

  • Add your code to the app


  • Make sure the “Copy items if needed” is unchecked.


  • This is the end result


  • Disable the Build step



  • Set the Deployment target version so it’s now larger than your device iOS version


  • Select the target device


Launch the debugger

You have a few options to debug an app

  1. Either choose Debug -> Attach to process... and select the app from there

  2. Or choose the Attach to process by PID or Process name


  3. Start the app on the device

  4. In Edit Scheme add the .app folder as the executable

Debug symbols

To use lldb, the execution must be paused

  • Add the .dSYM path to lldb

      (lldb) add-dsym <PathTo.dSYM>


  • Verify that lldb read the symbols successfully

      (lldb) image list <AppName>

Path mappings

  • Add the engine source (change accordingly for your need)

      (lldb) settings set target.source-map /Users/builder/ci/builds/engine-ios-64-master/build /Users/mathiaswesterdahl/work/defold
      (lldb) settings append target.source-map /private/var/folders/m5/bcw7ykhd6vq9lwjzq1mkp8j00000gn/T/job4836347589046353012/upload/videoplayer/src /Users/mathiaswesterdahl/work/projects/extension-videoplayer-native/videoplayer/src
    • It’s possible to get the job folder from the executable. The jobfolder is named like so job1298751322870374150, each time with a random number.

        $ dsymutil -dump-debug-map <executable> 2>&1 >/dev/null | grep /job
  • Verify the source mappings

      (lldb) settings show target.source-map

You can check what source file a symbol was originating from using

(lldb) image lookup -va <SymbolName>


  • Open a file in the project view, and set a breakpoint



Check UUID of binary

In order for the debugger to accept the .dSYM folder, the UUID need to match the UUID of the executable being debugged. You can check the UUID like so:

$ dwarfdump -u <PathToBinary>