当遇到This action could not be completed 或者 You do not have enough access privileges for this operation这个问题时，主要是因为 iTunes 不能获取到Shared 这个文件夹。
解释如下：
iTunes creates a hidden folder in this directory called "SC Info," which needs to be accessible by all users in order for iTunes Store authorizations to work properly. In some situations people may find that the entire Shared folder is missing, but in other situations the permissions for this folder may be set incorrectly.
解决方法如下：
在 Terminal 在运行以下命令：
1.mkdir -p /Users/Shared 2.sudo chmod -R 1777 /Users/Shared
原文如下：
https://www.cnet.com/news/itunes-crashing-with-access-privileges-error-in-10-6-7/
XCode 或者ITune 添加账号时，提示：This action could not be completed. 或者 Access Privileges
原文：http://www.cnblogs.com/lyz0925/p/7251698.html