When Apple introduced AirPrint to iOS, they made it incredibly easy to send files right from your iPhone, iPod touch, and iPad to any compatible Wi-Fi printer in the vicinity. Unfortunately, what Apple didn't do was bring Print to PDF (Export as PDF) along for the ride. At least, not yet...
One of the great features of OS X on the Mac is exactly that — the ability to export almost anything and everything quickly and easily to a PDF file. It's something I've mentioned in the past when discussing OS X Mavericks features that'd be great to see in iOS 8. It's my understanding Print/Export to PDF was in the pipeline years ago, but simply never got polished and pushed out.
Apple's engineers already put in long hours and tremendous effort, and there's an opportunity cost to everything. Working on feature A means the same person or team can't be working on feature B at the same time. Priorities. Trade-offs. Focus. That's how software development works. It could well be that Print/Export to PDF wasn't considered a priority, or something that enough of Apple's customers would use or benefit from. Or it could simply be sitting in the queue, patiently waiting its turn in the tentpoles.
Either way, I'd still like to see it in iOS. Sure, there are screenshots that can capture the pixels on the display, there are Share sheets that can grab content as-is and send it on its way, and there are Print to PDF apps in the App Store that offer some form of the same functionality. But the ability to take any page of text and images, in any app, and quickly, easily, turn it into a PDF? That's be the kind of magic we've come to expect from Apple.
See something, make something, want it wrapped up nicely and neatly? Tap Share, tap Print, tap PDF, store it up on iCloud or Share it by any of the usual methods. That'd be a great bullet point on Keynote. If you think so too, please join me in letting Apple know just how much we'd appreciate Print to PDF in iOS 8!