When running npm run ios
some time an error comes
$ react-native-scripts ios
Starting packager...
Starting simulator...
Unable to check Xcode version: Error: Process exited with non-zero code: 1
Failed to start simulator:
Unable to verify Xcode and Simulator installation.
Exiting...
The error can come if you don’t have any command line tool selected in xcode .To resolve the issue go to
Xcode->preferences -> Locations-> command line tools and select the command line tool as shown in image below.
![unable to verify xcode and simulator installation.](https://3.bp.blogspot.com/-tD_SKEFIPXk/W4PhXxW8D8I/AAAAAAAAKAI/NFIEGvCibmY-N-Z5awPqJ9vnfW_nsdkFQCLcBGAs/s1600/Screen%2BShot%2B2018-08-27%2Bat%2B4.44.41%2BPM.png)