Xcode10:Multiple commands produce '/Users/my/Library/Developer/Xcode/DerivedData/APP-ftjietavhqivelbnowzqyjzcvedu/Build/Products/Debug-iphonesimulator/
解决方法
(也就是使用旧版构建系统进行编译):
you open xcode and go to ( file > workspace settings) and change value build system to "Legacy build system" and build again.
默认选择的是:user build system,改成"Legacy build system" 即可。