Environment
Mac OS X Version 10.11.3 (15D21) Xcode Version 7.2 (7C68) Simulator Version 9.2 (SimulatorApp-643) react-native-cli 0.1.10 node v5.5
Adding sudo in front of all commands solves the problem.
sudo
sudo react-native init ProjectName sudo chmod 777 ProjectName cd ProjectName sudo react-native run-ios