Printing from your iPhone using iOS 8 is relatively easy, thanks to AirPrint. If your printer is AirPrint-ready, as most popular printers now are, you can print from apps on your iPhone, usually via the Share menu. If you have not updated to iOS 8.1, make sure to do so. AirPrint problems were reported when iPhone users updated to iOS 8.0, which were thereafter resolved with the 8.1 update. To find out if your printer is AirPrint ready, check for your model on Apple's AirPrint page.
If your printer is not AirPrint-ready, check iTunes to see if your printer's manufacturer has an iTunes app. If not, download the PrintCentral Pro app from iTunes. You will not be able to print from directly inside your apps, but you can use the PrintCentral Pro app to print documents from your iPhone.
Tap on the "Sharing" icon at the bottom of the screen on the page or in the document you want to print.
Select "Print" from the Sharing menu that pops up. You might need to swipe to the right in the menu to see the Print option.
Tap on "Select Printer" from the Printer Options page. You can also select the number of copies you want printed.
Select the make and model of your printer you want from the list of Wi-Fi printers available to your iPhone.
Tap "Print" on the Printer Options page. This will send the print job to your printer. A pop-up message will confirm that the job is being sent.