After the mac is upgraded to 10.13, you cannot use brew to install software. Solution sudo mkdir/usr/local/Cellar sudo chmod a+w/usr/local/Cellar sudo mkdir/usr/local/opt
Cause: The solution to upgrade xcode manually 1. Copy an old SDK and rename it to the SDK version required for real machine testing;To do this, find the path:/Applications/Xcode. app/Contents/Developer/Platforms/iPhone