GetInnerHeight = function (iOS)
{

    if (!iOS)
    {
        return window.innerHeight;
    }

    var axis = Math.abs(window.orientation);

    var size = { w: 0, h: 0 };

    var ruler = document.createElement('div');

    ruler.setAttribute('style', 'position: fixed; height: 100vh; width: 0; top: 0');

    document.documentElement.appendChild(ruler);

    size.w = (axis === 90) ? ruler.offsetHeight : window.innerWidth;
    size.h = (axis === 90) ? window.innerWidth : ruler.offsetHeight;

    document.documentElement.removeChild(ruler);

    ruler = null;

    if (Math.abs(window.orientation) !== 90)
    {
        return size.h;
    }
    else
    {
        return size.w;
    }
}
Attempts to determine the document inner height across iOS and standard devices.
Based on code by @tylerjpeterson

@function Phaser.DOM.GetInnerHeight
@since 3.16.0

@param {boolean} iOS - Is this running on iOS?

@return {number} The inner height value.