I am trying to remove the "com.apple.quarantine" attribute in files placed in
~/Library/Containers/....../Library/Application Support.
Using NSTask and xattr leads to "Operation not permitted" messages in console. As second option I tried the header xattr.h using removexattr().
I also tried to add LSFileQuarantineEnabled to Info.plist. Calling xattr manually from Terminal works.
Seems like sandbox prevents xattr from deleting attributes using Objective-C.