Get and sort files in a folder

Scripting Forums AppleScriptObjC and Xcode
#1

It’s commonplace that I have to obtain files with a particular extension from one folder. I don’t recall where but I found the script included below. With one exception it does what I want, but I wondered if there might be any improvements:

on getFiles(sourceFolder, fileExtensions) -- sourceFolder is POSIX path and fileExtensions is list of file extensions
	set fileManager to current application's NSFileManager's defaultManager()
	set theFolder to current application's |NSURL|'s fileURLWithPath:sourceFolder
	set folderContents to fileManager's contentsOfDirectoryAtURL:theFolder includingPropertiesForKeys:{} options:(current application's NSDirectoryEnumerationSkipsHiddenFiles) |error|:(missing value)
	set theFiles to current application's NSPredicate's predicateWithFormat_("pathExtension.lowercaseString IN %@", fileExtensions)
	set theFiles to folderContents's filteredArrayUsingPredicate:theFiles
	return theFiles as list
end getFiles

I need the returned list to be sorted by name in ascending order. I added a sort routine to the script but received an unrecognized-selector error, presumably because I cannot sort URL’s in this manner. I looked at the NSArrray and NSURL documentation but didn’t find a solution. How can I fix this or is there a better way.

on getFiles(sourceFolder, fileExtensions) -- sourceFolder is POSIX path and fileExtensions is list of file extensions
	set fileManager to current application's NSFileManager's defaultManager()
	set theFolder to current application's |NSURL|'s fileURLWithPath:sourceFolder
	set folderContents to fileManager's contentsOfDirectoryAtURL:theFolder includingPropertiesForKeys:{} options:(current application's NSDirectoryEnumerationSkipsHiddenFiles) |error|:(missing value)
	set theFiles to current application's NSPredicate's predicateWithFormat_("pathExtension.lowercaseString IN %@", fileExtensions)
	set theFiles to folderContents's filteredArrayUsingPredicate:theFiles
	set sortedFiles to (theFiles's sortedArrayUsingSelector:"compare:") -- error "-[NSURL compare:]: unrecognized selector sent to instance 0x600001825e00" number -10000
	return sortedFiles as list
end getFiles

Thanks for the help.

#2

NSURL instances cannot be sorted with the compare selector – as stated by the error – because NSURL doesn’t represent a single value like a string.

A solution is to use a NSSortDescriptor which sorts the array by the file name (in terms of NSURL the last path component)

on getFiles(sourceFolder, fileExtensions) -- sourceFolder is POSIX path and fileExtensions is list of file extensions
	set fileManager to current application's NSFileManager's defaultManager()
	set theFolder to current application's |NSURL|'s fileURLWithPath:sourceFolder
	set folderContents to fileManager's contentsOfDirectoryAtURL:theFolder includingPropertiesForKeys:{} options:(current application's NSDirectoryEnumerationSkipsHiddenFiles) |error|:(missing value)
	set theFiles to current application's NSPredicate's predicateWithFormat_("pathExtension.lowercaseString IN %@", fileExtensions)
	set theFiles to folderContents's filteredArrayUsingPredicate:theFiles
	set sortDescriptors to current application's NSArray's arrayWithObject:(current application's NSSortDescriptor's sortDescriptorWithKey:"lastPathComponent" ascending:true)
	set sortedFiles to (theFiles's sortedArrayUsingDescriptors:sortDescriptors)
	return sortedFiles as list
end getFiles
#3

Thanks Stefan. That worked great.

FWIW, I ran some timing tests on the above script and the Finder equivalent. The test folder contained 20 PDF, 20 PNG, and 20 TXT files, and I set the scripts to get PDF files only. The first-run timing results were:

ASObjC - 0.028 seconds

Finder - 1.261 seconds

The ASObjC result is with the Foundation framework in memory, which would normally be the case if ASObjC is regularly used.