Running React Native app on iOS Simulator hangs while building during ComputeTargetDependencyGraph

Question

I have a React Native app that I'm trying to run on the iOS Simulator on my laptop. To launch this, I do npm start from my project directory, which shows the nice Metro icon then

r - reload the app
d - open developer menu
i - run on iOS
a - run on Android

Before, when I hit i, it would work the majority of the time but sometimes get hung up on a particular step. After some recent changes and installing a new library (and successfully doing npx pod-install), it's now getting hung up on the same step every time.

The step is: after hitting i, I get this:

info Opening the app on iOS...
info Found Xcode workspace "notoapprn.xcworkspace"
info Found booted iPhone 14
info Launching iPhone 14
info Building (using "xcodebuild -workspace notoapprn.xcworkspace -configuration Debug -scheme notoapprn -destination id=5655375F-31B9-47EC-9DD1-196F4CB8C86D")

info 💡 Tip: Make sure that you have set up your development environment correctly, by running react-native doctor. To read more about doctor command visit: https://github.com/react-native-community/cli/blob/main/packages/cli-doctor/README.md#doctor

Command line invocation:
    /Applications/Xcode.app/Contents/Developer/usr/bin/xcodebuild -workspace notoapprn.xcworkspace -configuration Debug -scheme notoapprn -destination id=5655375F-31B9-47EC-9DD1-196F4CB8C86D

User defaults from command line:
    IDEPackageSupportUseBuiltinSCM = YES

Prepare packages

ComputeTargetDependencyGraph
note: Building targets in dependency order
note: Target dependency graph (68 targets)
Target 'notoapprn' in project 'notoapprn'
        ➜ Explicit dependency on target 'NotoMeShare' in project 'notoapprn'
        ➜ Implicit dependency on target 'Pods-notoapprn' in project 'Pods' via file 'libPods-notoapprn.a' in build phase 'Link Binary'
        ➜ Implicit dependency on target 'CocoaAsyncSocket' in project 'Pods' via options '-lCocoaAsyncSocket' in build setting 'OTHER_LDFLAGS'
        ➜ Implicit dependency on target 'DoubleConversion' in project 'Pods' via options '-lDoubleConversion' in build setting 'OTHER_LDFLAGS'
...

and many more lines noting Targets and their explicit / implicit dependencies. However, when it gets hung up, it'll literally print only part of a line, then nothing continues to happen, eg:

        ➜ Implicit dependency on target 'RCT-Folly' in project 'Pods' via options '-lRCT-Folly' in build setting 'OTHER_LDFLAGS'
        ➜ Implicit dependency on target 'RCTTypeSafety' in project 'Pods' via options '-lRCTTypeSafety' in build setting 'OTHER_LDFLAGS'
        ➜ Implicit dependency on target 'RNShareMenu' in project 'Pods' via options '-lRNShareMenu' in build setting 'OTHER_LDFLAGS'
        ➜ Implicit dependency on target 'React-Codegen' in project 'Pods' via op

The line is seemingly broken partway through.

More mysteriously, if I cancel this command and try running it all again, it'll get hung up again but possibly in a different spot in the list of targets/dependencies.

Any tips on debugging this?

Answer 1

I'm guessing what this is is a silent failure.

To build it another way, I went to XCode and tried to build the app with a target of the iPhone 14 simulator. When that tried to build, it threw errors - this helped me actually find the bug and fix it.

I'm guessing when you try to do it via the Terminal / Metro, it just silently fails, thus making it seem like it hangs in the middle of the targets and dependencies list.