How do you disable viewport zooming on Mobile Safari?

For the people looking for an iOS 10 solution, user-scaleable=no is disabled in Safari for iOS 10. The reason is that Apple is trying to improve accessibility by allowing people to zoom on web pages.

From release notes:

To improve accessibility on websites in Safari, users can now pinch-to-zoom even when a website sets user-scalable=no in the viewport.

So as far as I understand, we are sh** out of luck.

Edit: may not work after iOS 10, please see touch-action based solution below.

Your code is displaying attribute double quotes as fancy double quotes. If the fancy quotes are present in your actual source code I would guess that is the problem.

This works for me on Mobile Safari in iOS 4.2.

<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />