If the text in your document is editable, when you select a line of text you'll see an option to Correct Text. Choosing this option changes the entire line your cursor is on into an editable line of text. This tool allows for minor edits of one or two words in a single line, but cannot be used to edit entire paragraphs. And when working on sophisticated documents that include multiple columns or text boxes containing content unrelated to the text you're editing, PDFpen often selected text across boundaries, making it impossible to make changes without affecting the unrelated text.
While, overall, I am happy with the tools PDFpen offers for editing and marking up PDF documents, I am disappointed to report that I found both versions of the app to be rather buggy. I had a number of issues with the iPad app, including incompletely rendered pages, pages out of focus, and stuttering or multi-second pauses when scrolling up or down on a page. The iPhone app wasn't much better. On my 5S scrolling was never an issue, but sometimes pages within documents appeared as blank pages, even though the thumbnails showed that there was text. I also found that if the text I was selecting was near the top of the document and therefore also near the toolbar, the iOS magnifying glass that shows where your cursor is displayed the text but did not show the cursor.
Version 1.7 of PDFpen for iPad and iPhone is a double-edged sword. It offers a number of powerful and useful tools for marking up and editing your PDF documents on your iOS device. But at present it is fraught with a number of intermittent and significant bugs that may render it difficult to use for its intended purpose. While I can recommend it as a great tool, you may want to wait for a future update to avoid potential frustration.
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