卡在Authenticating with iTunes Store（This action could not be completed. Try Again -22421）的解决方法

上传App Store时候如果遇到卡在卡在Authenticating with iTunes Store或者提示This action could not be completed. Try Again -22421错误的解决方法如下：

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打开Terminal终端，输入以下命令

cd ~
mv .itmstransporter/ .old_itmstransporter/
"/Applications/Xcode.app/Contents/Applications/Application Loader.app/Contents/itms/bin/iTMSTransporter"

iTMSTransporter 会自动更新, 更新完后就可以用XCode再次上传了。