var metas = document.getElementsByTagName('meta');

var i;

if (navigator.userAgent.match(/iPhone/i)) {

for (i=0; i<metas.length; i++) {

if (metas[i].name == "viewport") {

metas[i].content = "width=device-width, minimum-scale=1.0, maximum-scale=1.0";

}

}

document.addEventListener("gesturestart", gestureStart, false);

}

function gestureStart() {

for (i=0; i<metas.length; i++) {

if (metas[i].name == "viewport") {

metas[i].content = "width=device-width, minimum-scale=0.25, maximum-scale=1.6";

}

}

}