Cannot drag and drop cell onto collectionview

I customized a UIViewController through xib, and then put a UICollectionView on it, and then I wanted to drag a UICollectionViewCell onto UICollectionView (just like UITableView ), but I couldn"t drag it up.

Ios
Apr.17,2021

xib in tableView and collectionView cannot be directly put into cell , while storyBoard can

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b4213f-2bd60.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b4213f-2bd60.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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