When refactoring the project for many times and the code fails to compile without errors, you can try to delete the DerivedData directory. The DerivedData directory is the compilation cache of Xcode, and the path is ~/Library/Developer/Xcode/DerivedData .
The specific operation can be as follows:
First, select "Go to Folder" under "Go" on the menu of "Finder", enter ~/Library/Developer/Xcode/DerivedData and confirm, then you will enter DerivedData, and then the folder in the Just delete all the content.
Of course, if this is too troublesome every time, you can make a " stand -in" for the DerivedData folder on the desktop, and it will be much more convenient to delete the content in DerivedData later.