There are three basic types of PDF files, but not all of them are searchable.
- Text-based or “true” PDFs are created from a word processor like Apple Pages or Microsoft Word. These are searchable.
- Image-based PDFs contain pages that are actually screenshots or images created from a scanner. Though the pages might contain text, the text is actually part of the image and thus is not searchable. A simple test is to try to select the text; if it can't be selected, chances are the file is not searchable. If you happen to have an image-based PDF, you will need the help of a third-party program to make it searchable. See the next type.
- OCR’d or “made-searchable” PDFs: Image-based PDFs that have been processed by a special Optical Character Recognition program to include an invisible, searchable text layer.
If you can't search an imported PDF that should be searchable, tap the Gear icon in the top-right corner of the Library view > Settings > Search Indexing, and make sure the option is enabled.
If you still have search issues with the file, please send it to us for a look.