运行IOS虚拟机的时候出现了这样的错误提示，请问如何解决

 Error: /Users/liwei/my-app/platforms/ios/cordova/run: Command failed with exit code 1
    at ChildProcess.whenDone (/usr/local/lib/node_modules/cordova/node_modules/cordova-lib/src/cordova/superspawn.js:135:23)
    at ChildProcess.emit (events.js:98:17)
    at maybeClose (child_process.js:756:16)
    at Process.ChildProcess._handle.onexit (child_process.js:823:5)