Differences between Create groups and Create folder references when Xcode introduces external files, xcodereferences
1. Using Create groups, we can manually add a Group in the project (right-click and choose New Group), but the manually added groups does not actually exist in the project directory, the files added to the groups are still located in the original location, but the groups files introduced from outside are not. Once a groups object is created or added, it is in the form of a yellow folder. When you want to use the header file of a class in the folder, you can directly Add a reference to it. This is because the cpp file under groups will be compiled.
2. Use the Create folder references method to Create a reference for a file. The file exists in a blue folder and will not be compiled. Therefore, you must add the file path when using it, otherwise, the reference data is empty.