The first step is to download and install iFunBox on the computer and install it on the iphone.
Step 2, open iFunBox on the computer and connect the ios device to the computer.
Step 3, enter the directory iFunBox file management/user applications/daily sounds/documents.
The fourth step is to group the music files into a folder, and the folder name is the group name. Drag it to this directory and you can see it every day when the iphone is turned on.