Why Apple loves to upgrade. The 10.12.6 I used before was fine. Later, the xcode projects that were developed and downloaded were all packaged with new software, and my old version could not be matched. If Apple wants to upgrade xcode, it must upgrade the osx system.
At the beginning, I downloaded the AppStore system. After restarting, it always showed that the white apple was loading, but I couldn't enter the system. -> failed