property |NSURL| : a reference to current application’s |NSURL|
property NSArray : a reference to current application’s NSArray
property NSPredicate : a reference to current application’s NSPredicate
property NSFileManager : a reference to current application’s NSFileManager
property NSURLPathKey : a reference to current application’s NSURLPathKey
property NSMutableArray : a reference to current application’s NSMutableArray
property NSSortDescriptor : a reference to current application’s NSSortDescriptor
property NSURLIsPackageKey : a reference to current application’s NSURLIsPackageKey
property NSURLIsDirectoryKey : a reference to current application’s NSURLIsDirectoryKey
property NSURLTypeIdentifierKey : a reference to current application’s NSURLTypeIdentifierKey
property NSURLContentModificationDateKey : a reference to current application’s NSURLContentModificationDateKey
property NSDirectoryEnumerationSkipsHiddenFiles : a reference to current application’s NSDirectoryEnumerationSkipsHiddenFiles

–set inFiles to (choose file of type {"pdf"} with prompt "Choose your PDF files:" with multiple selections allowed)
tell application "Finder"
　　set inFiles to selection as alias list
end tell

if inFiles = {} then return

–指定のAlias listのうちPDFのみ抽出
set filRes1 to filterAliasListByUTI(inFiles, "com.adobe.pdf") of me

–選択中のファイルのうちの１つから親フォルダを求め、出力先ファイルパスを組み立てる
set outPathTarg to POSIX path of (first item of filRes1)
set pathString to current application’s NSString’s stringWithString:outPathTarg
set newPath to (pathString’s stringByDeletingLastPathComponent()) as string
set destPosixPath to newPath & "/" & ((current application’s NSUUID’s UUID()’s UUIDString()) as string) & ".pdf"

combinePDFsAndSaveIt(filRes1, destPosixPath) of me

on combinePDFsAndSaveIt(inFiles, destPosixPath)
　　set inFilesSorted to my filesInListSortFromOldToNew(inFiles)
　　
　　— make URL of the first PDF
　　set inNSURL to current application’s |NSURL|’s fileURLWithPath:(POSIX path of item 1 of inFilesSorted)
　　set theDoc to current application’s PDFDocument’s alloc()’s initWithURL:inNSURL
　　
　　— loop through the rest
　　set oldDocCount to theDoc’s pageCount()
　　set inFilesSorted to rest of inFilesSorted
　　
　　repeat with aFile in inFilesSorted
　　　　set inNSURL to (current application’s |NSURL|’s fileURLWithPath:(POSIX path of aFile))
　　　　set newDoc to (current application’s PDFDocument’s alloc()’s initWithURL:inNSURL)
　　　　
　　　　set newDocCount to newDoc’s pageCount()
　　　　repeat with i from 1 to newDocCount
　　　　　　set thePDFPage to (newDoc’s pageAtIndex:(i – 1)) — zero-based indexes
　　　　　　(theDoc’s insertPage:thePDFPage atIndex:oldDocCount)
　　　　　　set oldDocCount to oldDocCount + 1
　　　　end repeat
　　　　
　　end repeat
　　
　　set outNSURL to current application’s |NSURL|’s fileURLWithPath:destPosixPath
　　(theDoc’s writeToURL:outNSURL)
end combinePDFsAndSaveIt

on filesInListSortFromOldToNew(aliasList)
　　set keysToRequest to {NSURLPathKey, NSURLIsPackageKey, NSURLIsDirectoryKey, NSURLContentModificationDateKey}
　　
　　set valuesNSArray to NSMutableArray’s array()
　　repeat with i in aliasList
　　　　set oneNSURL to (|NSURL|’s fileURLWithPath:(POSIX path of i))
　　　　(valuesNSArray’s addObject:(oneNSURL’s resourceValuesForKeys:keysToRequest |error|:(missing value)))
　　end repeat
　　
　　set theNSPredicate to NSPredicate’s predicateWithFormat_("%K == NO OR %K == YES", NSURLIsDirectoryKey, NSURLIsPackageKey)
　　set valuesNSArray to valuesNSArray’s filteredArrayUsingPredicate:theNSPredicate
　　
　　set theDescriptor to NSSortDescriptor’s sortDescriptorWithKey:(NSURLContentModificationDateKey) ascending:true
　　set theSortedNSArray to valuesNSArray’s sortedArrayUsingDescriptors:{theDescriptor}
　　
　　— extract just the paths and convert to an AppleScript list
　　return (theSortedNSArray’s valueForKey:(NSURLPathKey)) as list
end filesInListSortFromOldToNew

–Alias listから指定UTIに含まれるものをPOSIX pathのリストで返す
on filterAliasListByUTI(aList, targUTI)
　　set newList to {}
　　repeat with i in aList
　　　　set j to POSIX path of i
　　　　set tmpUTI to my retUTIfromPath(j)
　　　　set utiRes to my filterUTIList({tmpUTI}, targUTI)
　　　　if utiRes is not equal to {} then
　　　　　　set the end of newList to j
　　　　end if
　　end repeat
　　return newList
end filterAliasListByUTI

–指定のPOSIX pathのファイルのUTIを求める
on retUTIfromPath(aPOSIXPath)
　　set aURL to |NSURL|’s fileURLWithPath:aPOSIXPath
　　set {theResult, theValue} to aURL’s getResourceValue:(reference) forKey:NSURLTypeIdentifierKey |error|:(missing value)
　　
　　if theResult = true then
　　　　return theValue as string
　　else
　　　　return theResult
　　end if
end retUTIfromPath