错误：
Your account already has an Apple Development signing certificate for this machine, but its private key is not installed in your keychain. Xcode can create a new one after revoking your existing certificate.
如下图：
WX20200818-182650@2x.png
登录上了AppleID账号也不行，解决办法：
参考文章：https://www.cnblogs.com/ruiati/p/9121768.html
Xcode - Preferences - Accounts - 登录AppleID账号后，右侧Team为Agent的team名称，双击，弹出，左下角下拉选择Apple development
WX20200818-183203@2x.png
