Xcode 11 beta 4 error: Command CompileSwiftSources failed with a nonzero exit code

There is a known issue with Cocoapods and Xcode 11 Beta 4 where inhibit_all_warnings! causes arguments to be set for Swift which do not compile. Removing this inhibit resolves the issue, and Swift warnings can be inhibited with SWIFT_SUPPRESS_WARNINGS = YES on targets instead.

CocoaPods had a fix for this that got released as part of CocoaPods 1.7.5.

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Below is the answer preceding the 1.7.5 release:

_{If you need to use Xcode 11 Beta 4 in the mean time, you could install a patched version of CocoaPods from that pull request:}

_{1. Open Gemfile, replace gem 'cocoapods' with}

gem 'cocoapods', :git => 'https://github.com/dnkoutso/CocoaPods.git', :branch => "swift_compiler_warnings"

_{2. Run bundle install and bundle exec pod install}

_{Keep in mind, this is a temporary solution.}

The latest version of CocoaPods (1.7.5) has this issue fixed!

1. In Terminal run

   sudo gem update cocoapods

2. And then, on your project directory

   pod install