How do I fix "no speakable content could be found on the screen"?

Hello!

Thanks in advance for taking the time to read my question.

I have listened to many "digital books" in the kindle app and books app using the iphone's text-to-speech feature.

However, I encountered a HUGE set back!

I purchased a $80 "physical book", hoping that I could use the iphone's camera with one of those "scan into pdf" apps and have the iphone's text-to-speech feature read the book to me. I was wrong!

I used iScanner (paid) and Adobe Scan (free) apps to capture a photo and turn it into a pdf, but when I tell the iphone to "speak screen", I get the "no speakable content could be found on the screen" message. Adobe Scan recognizes that the photo/pdf contains text and allows me to search for text, but the text ins't recognized by the text-to-speech feature.

Is there an app out there that will allow me to take a photo that the text-to-speech feature will recognize?

What other work around can you guys think of?

Thanks again!