If you have a visual impairment that makes it difficult for you to read text or see icons on your iPhone or iPad, the zoom feature is a great accessibility option that allows you to magnify text and even your Home screen, but only when you need to. While larger and bolder text helps, enabling zoom adds even more flexibility on the fly. All you've got to do is enable it first!
How to enable zoom for better visual accessibility on your iPhone or iPad
Launch the Settings app on your iPhone or iPad.
Tap on General.
Tap on Accessibility.
Under the Vision section, tap on Zoom.
Turn the Zoom option On.
Once you've got Zoom enabled, you can use it on the fly. Here's how to use it:
Double tap with three fingers anywhere on the screen to enable and disable zoom. You can do this from pretty much anywhere.
Drag three fingers around the screen to pan around and move to another area of the screen.
Use one or two fingers to scroll in the particular section that is on the screen.
That's it! You're good to go! If you ever decide you don't like zoom enabled, you can easily disable it by hopping back into the Settings app again.
Note: Originally posted April 2013. Updated July 2014.