Running react-native apps on iOS emulators

So I am trying to run a simple react-native app on an iPhone 11 - 13.2.2 emulator.

I type npm run ios but I get this back.

** BUILD FAILED **


The following build commands failed:
        CompileC /Users/theodosiostziomakas/Desktop/React-Native/confusion/ios/build/confusion/Build/Intermediates.noindex/confusion.build/Debug-iphonesimulator/confusion.build/Objects-normal/x86_64/AppDelegate.o /Users/theodosiostziomakas/Desktop/React-Native/confusion/ios/confusion/AppDelegate.m normal x86_64 objective-c com.apple.compilers.llvm.clang.1_0.compiler
        CompileC /Users/theodosiostziomakas/Desktop/React-Native/confusion/ios/build/confusion/Build/Intermediates.noindex/confusion.build/Debug-iphonesimulator/confusion.build/Objects-normal/x86_64/main.o /Users/theodosiostziomakas/Desktop/React-Native/confusion/ios/confusion/main.m normal x86_64 objective-c com.apple.compilers.llvm.clang.1_0.compiler
(2 failures)

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! @ ios: `react-native run-ios`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the @ ios script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/theodosiostziomakas/.npm/_logs/2019-11-16T12_38_06_754Z-debug.log

I used npm install but still nothing. How to fix that error?

Thanks, Theo.