When Xcode introduces external files, the difference between create groups or Create folder references is selected

First, using create groups we can manually add a groups in the project (right click to select New Group), but the manually added groups does not actually exist in the project directory, the file that is added to the groups is still in its original location, But the groups that came in from the outside would not be so. Once groups is created or added, it exists in the form of a yellow folder , and you can add its references directly when you want to use a header file for a class in a folder. because the CPP file under groups will be compiled.

Second, the use of the Create folder references method simply creates a reference to the file, is in the Blue folder exists , These files will not be compiled , so in the use of the need to join its path, otherwise it will cause the reference data is empty.

When Xcode introduces external files, the difference between create groups or Create folder references is selected