property |NSURL| : a reference to current application’s |NSURL|
property NSPredicate : a reference to current application’s NSPredicate
property NSFileManager : a reference to current application’s NSFileManager
property PDFDocument : a reference to current application’s PDFDocument
property NSMutableArray : a reference to current application’s NSMutableArray
property NSURLIsDirectoryKey : a reference to current application’s NSURLIsDirectoryKey
property NSDirectoryEnumerationSkipsHiddenFiles : a reference to current application’s NSDirectoryEnumerationSkipsHiddenFiles
property NSDirectoryEnumerationSkipsPackageDescendants : a reference to current application’s NSDirectoryEnumerationSkipsPackageDescendants
property NSDirectoryEnumerationSkipsSubdirectoryDescendants : a reference to current application’s NSDirectoryEnumerationSkipsSubdirectoryDescendants

set aFol to POSIX path of (choose folder with prompt "Choose folder" default location (path to pictures folder))
set targPDF to POSIX path of (choose file name with prompt "Choose File Name" default location (path to desktop folder) default name ((do shell script "uuidgen") & ".pdf"))
set pRes to gatherEachFirstPage(aFol, targPDF) of me

on gatherEachFirstPage(aFol, targPDF)
　　set aURL to (|NSURL|’s fileURLWithPath:targPDF)
　　
　　set outPDFdoc to PDFDocument’s alloc()’s init()
　　
　　set aList to my getFilesByExtension:{"pdf"} fromDirectory:(aFol)
　　
　　set outPDFPageCount to 0
　　repeat with i in aList
　　　　–集めたPDFの１ページ目を取得
　　　　set bURL to (|NSURL|’s fileURLWithPath:(POSIX path of i))
　　　　set bPDFdoc to (PDFDocument’s alloc()’s initWithURL:bURL)
　　　　set bPage to (bPDFdoc’s pageAtIndex:0) –first page
　　　　
　　　　–まとめ先のPDFに追記
　　　　(outPDFdoc’s insertPage:bPage atIndex:outPDFPageCount)
　　　　set outPDFPageCount to outPDFPageCount + 1
　　end repeat
　　
　　return (outPDFdoc’s writeToURL:aURL) as boolean
end gatherEachFirstPage

–指定フォルダ内の指定拡張子のファイルを抽出する
on getFilesByExtension:listOfExtensions fromDirectory:sourceFolder
　　set fileManager to NSFileManager’s defaultManager()
　　set aURL to |NSURL|’s fileURLWithPath:sourceFolder
　　set theOptions to ((NSDirectoryEnumerationSkipsPackageDescendants) as integer) + ((NSDirectoryEnumerationSkipsHiddenFiles) as integer)
　　set directoryContents to fileManager’s contentsOfDirectoryAtURL:aURL includingPropertiesForKeys:{} options:theOptions |error|:(missing value)
　　set foundItemList to NSPredicate’s predicateWithFormat_("pathExtension.lowercaseString IN %@", listOfExtensions)
　　set foundItemList to directoryContents’s filteredArrayUsingPredicate:foundItemList
　　# Return as a list POSIX Paths
　　set foundItemList to (foundItemList’s valueForKey:"path") as list
　　return foundItemList
end getFilesByExtension:fromDirectory: