The first part opens the keychain, the
second part selects login, and the type selects the certificate as shown in the figure below
The third part is in the upper left corner menu of the keychain, click 'Show' -> 'Show expired certificates', as shown in the figure below
After deleting the expired certificate 'Apple Worldwide Developer RTelations Certification Atuhority' with a fork
At the same time, find the same expired certificate under the 'system' keychain, as shown below
Similarly , delete the expired certificate 'Apple Worldwide Developer RTelations Certification Atuhority' with a fork, and the user will be prompted to enter the system login password for verification. Verify and delete.
The fourth part goes here (http://developer.apple.com/certificationauthority/AppleWWDRCA.cer ) to download the new Apple system certificate, double-click to import to solve the problem of "the issuer of this certificate is invalid", and then go back and look at the original certificate. becomes valid, as shown in the following figure
Hope it can help students who encounter the same problem.