React-native: watchman--no-pretty get-sockname zurückgegeben mit Exit-Code null

Ich folge der Starter-Anleitung von der Seite "react native". Beim Ausführen des Befehls react-native run-ios ich die folgende Fehlermeldung:

watchman--no-pretty get-sockname returned with exit code null dyld: Library not loaded: /usr/local/opt/pcre/lib/libpcre.1.dylib
  Referenced from: /usr/local/Cellar/watchman/4.5.0/libexec/bin/watchman
  Reason: image not found

 ERROR  watchman--no-pretty get-sockname returned with exit code null dyld: Library not loaded: /usr/local/opt/pcre/lib/libpcre.1.dylib
  Referenced from: /usr/local/Cellar/watchman/4.5.0/libexec/bin/watchman
  Reason: image not found

Error: watchman--no-pretty get-sockname returned with exit code null dyld: Library not loaded: /usr/local/opt/pcre/lib/libpcre.1.dylib
  Referenced from: /usr/local/Cellar/watchman/4.5.0/libexec/bin/watchman
  Reason: image not found

mein System: macos 10.11.6, Knoten 6.2.2