double val; CFNumberGetValue(bytesCompleted, kCFNumberDoubleType, &val); if (progressIndicator) { [progressIndicator setDoubleValue:val]; [progressIndicator displayIfNeeded]; }

if you copy one big file, this works very well, but if you copy a batch of files, the display seems confusing as multiple files are being copied in the same time, how to schedule the copying in such a way that only one file is being copied at one time?

Seriously, though, globals are generally bad, but what seems really awkward here is the limitation of one progress indicator, period. Especially since there’s a context parameter (a standard Cocoa/Carbon callback pattern) that you could be using.

Separately, it might not be a bad idea to use FSPathCopyObjectAsync() instead of FSCopyObjectAsync(), since in Cocoa usually you have paths rather than FSRefs, and creating an FSRef requires going through -fileSystemRepresentation anyway. (Probably it would be the same code executed underneath, but it’s less to think about.)