Fix Cannot Search or Highlight Text in PDFs on iOS
Question details
The user is unable to use the text search and highlighting tools on specific PDF files when using their iOS device, despite these features working fine on a Windows computer.
- Product
- Adobe Acrobat for iOS
- Device & OS
- iOS
- Scenario
- Trying to search for keywords or highlight text in a PDF document using an iPhone or iPad.
- Observed behavior
- The search and highlight functions fail to recognize or select text in certain PDFs on iOS, while working normally on a desktop operating system.
Verify whether the PDF consists of selectable text or is a scanned image by tapping and dragging over the words. Also, ensure your iOS device is updated to the latest version.
Convert Scanned PDFs Using OCR
If the PDF is a scanned image, the text is essentially a picture. Using an Optical Character Recognition (OCR) tool will generate a selectable and searchable text layer.
A very common reason text cannot be highlighted on mobile apps is that the PDF was generated from a scanner without an OCR layer applied. While some robust desktop apps attempt to bypass this, mobile apps often require a clean text layer.
Use a desktop PDF editor with OCR capabilities or a trusted online OCR converter tool.
Upload your problematic PDF and select the option to perform OCR. Ensure the language settings match the language used in your document.
Save the newly generated text-searchable PDF to your computer and transfer it back to your iOS device via cloud storage or email.
Re-export to Fix Text Encoding Issues
Re-exporting or re-printing the PDF on a computer can resolve hidden encoding or structure issues that prevent iOS apps from reading the text layer correctly.
Edit, Search, and Highlight PDFs Seamlessly with WPS Office
WPS Office provides a powerful PDF reader and editor for iOS, Windows, and Mac. If you are struggling with unselectable text, WPS Office offers built-in OCR and comprehensive PDF tools to ensure you can search, highlight, and annotate any document flawlessly directly on your mobile device.
- 1. Download WPS Office: Install the free WPS Office app from the App Store on your iOS device.
- 2. Open Your PDF: Launch WPS Office, navigate to your files, and open the problematic PDF.
- 3. Use Annotations and OCR: Tap the 'Tools' menu at the bottom to access Highlight and Search functions. If it is a scanned file, use the built-in OCR tool to make the text editable.
Frequently Asked Questions
Why can I highlight text in a PDF on Windows but not on iOS?
Different operating systems and PDF applications handle embedded fonts and text encoding differently. A desktop PDF viewer might compensate for complex or non-standard file structures, whereas a mobile app on iOS might strictly require standard encoding, causing it to fail at parsing the text layer.
How do I know if my PDF is a scanned image instead of text?
Try to zoom in closely on the document text. If the edges of the letters become pixelated or blurry, and you cannot place a blinking cursor between the individual letters, the PDF is likely a scanned image without an active text layer.
Can I fix unselectable PDF text directly on my iPhone?
Yes, you can use iOS applications that feature built-in Optical Character Recognition (OCR), such as WPS Office. These apps can scan the image elements of the PDF and generate a readable text layer directly on your mobile device without needing a computer.
Does file encryption prevent highlighting and searching on iOS?
Yes, if a PDF is protected with permission passwords, actions like copying, highlighting, or extracting text may be restricted. You would need to enter the permissions password to unlock full editing features.
