问FullScreen iFrame在iOS中使用Javascript [Safari]

EN

function setUpFullScreen() {
    document.cancelFullScreen = document.webkitCancelFullScreen || document.mozCancelFullScreen || document.cancelFullScreen;
    document.body.requestFullScreen = document.body.webkitRequestFullScreen || document.body.mozRequestFullScreen || document.body.requestFullScreen;
    document.onfullscreenchange = document.onfullscreenchange || document.onwebkitfullscreenchange || document.onmozfullscreenchange;
    if (document.addEventListener) {
        document.addEventListener('webkitfullscreenchange', fullscreenChangeHandler, false);
        document.addEventListener('mozfullscreenchange', fullscreenChangeHandler, false);
        document.addEventListener('fullscreenchange', fullscreenChangeHandler, false);
        document.addEventListener('MSFullscreenChange', fullscreenChangeHandler, false);
    }
}

function toggleFullScreen() {
    if (isFullScreen()) {
        trace("Exiting fullscreen.");
        document.querySelector("svg#fullscreen title").textContent = "Enter fullscreen";
        document.cancelFullScreen();
    } else {
        trace("Entering fullscreen.");
        document.querySelector("svg#fullscreen title").textContent = "Exit fullscreen";
        document.body.requestFullScreen();
    }
}

function isFullScreen() {
    return !!(document.webkitIsFullScreen || document.mozFullScreen || document.isFullScreen);
}

TypeError: document.body.requestFullScreen is not a function. (In 'document.body.requestFullScreen()', 'document.body.requestFullScreen' is undefined)