PDFKit background search
问题 I'm trying to run a search on a background thread using new iOS PDFKit framework. override func main() { if isCancelled { return } pdfDocument = PDFDocument.init(url: book.document.url)! pdfDocument.delegate = self pdfDocument.beginFindString("test", withOptions: [.caseInsensitive, .diacriticInsensitive]) (async) //pdfDocument.findString("test", withOptions: [.caseInsensitive, .diacriticInsensitive]) (sync) } The problem is that none of the PDFDocumentDelegate's methods isn't called and if I