iOS 'The sandbox is not sync with the Podfile.lock错误

出现以下错误时，

diff: /../Podfile.lock: No such file or directory 
diff: Manifest.lock: No such file or directory 
error: The sandbox is not in sync with the Podfile.lock. Run 'pod install' or update your CocoaPods installation.` 

关闭当前的工作空间，删除掉文件夹中的workspace，然后重新pod install，install完成之后，通过workspace打开工作空间，clean+build即可，如下所示

rm -rf MyProject.xcworkspace 
pod install 

在pod install之前，请确保已经执行pod setup命令。