The file “***.m” could not be un

The file “***.m” could not be unlocked.

Could not add write permission to the file because you do not own it. Try modifying the permissions of the file in the Finder or Terminal.
编辑主工程目录下的某一个文件，出现了locked，无法解锁。

finder中打开显示简介，文件权限查看本用户“读与写”，没有问题。尝试staff和everyone都改为“读与写”可以编辑了，原因暂时不明。