The web application version of Paperpile allows for text selection and then highlighting. For instance, I can select some text in my PDF and then hit the “1” key to highlight my selected text. This is a very natural and non-interruptive way of annotating. The IOS app requires that you first select the highlighter and then a color and then select what text you want to highlight.
It would be a great feature to be able to select text and then highlight – like on the web app – on the IOS app.