I'm implementing my own autocompletion on an <input> field inside a UIWebView, and the built-in keyboard autocompletion interferes with the user experience. Is there a way to use HTML or Javascript to signal to iOS that it shouldn't try to autocomplete?
In my comments I mentioned using the html attribute autocomplete but I tested it, and it doesn't address your issue. However, there is an attribute specific to Mobile Safari which may help. You could try turning off autocorrect like so:
<input type="text" id="your-field" autocorrect="off" />