iOS input focused inside fixed parent stops positi

问题:

The following happens on Mobile Safari iOS 6.1.2

Steps to reproduce

Create a position: fixed element with an <input type="text"> element inside it.

Actual result

1. Input - not focused

   The position of the fixed elements is correct when input is not focused.

   

2. Input - focused

   When the input is focused, the browser enters a special mode in which it does not update the position of the fixed elements any more (any fixed positioned element, not just the input's parent) and moves the whole viewport down in order to make the input's parent element sit in the center of the screen.

   See live demo: http://jsbin.com/oqamad/1/

   

Expected result

The position of the fixed elements is always respected.

Fix or workaround?

Any clues as how to force Safari to properly display the fixed elements would be helpful.

I would prefer a workaround which does not involve using position: absolute and setting an onscroll event handler.

回答1:

It's a well known bug on Safari, both on iPad and iPhone.

A workaround it's to change the position to absolute to all elements set with fixed position.

In case you are using Modernizr you could also target mobile devices this way:

---

jQuery code

---

$(document).ready(function() {

  if (Modernizr.touch) {

      $(document)

        .on('focus', 'input', function(e) {
            $('body').addClass('fixfixed');
        })

        .on('blur', 'input', function(e) {
            $('body').removeClass('fixfixed');
        });

      }

});

---

CSS

---

If I want to target just the header and footer for example, that are set with fixed position, when the class 'fixfixed' is added to the body I can change the position to absolute to all elements with fixed position.

.fixfixed header, .fixfixed footer {
  position: absolute;
}

回答2:

Position:Fixed has a lot of well known-bugs, you can check them here: Remysharp article. Probably you can still fix some of them using the answers from this question: CSS “position: fixed;” into iPad/iPhone?

Good luck!

回答3:

Yep, this is specifically an iOS safari issue since v5. If you use Chrome on iOS you'll notice it will work OK. The bodge I use to fix this is to create and add a style element to the body and subsequently delete it and then perform the focus on the element.

Don't ask me why this works, just too many hours of trial and error!

I've also noticed that after the first time this is fixed you don't have to perform the style trick for subsequent fixed positioned elements