下拉以在移动Web浏览器上刷新

Question

我正在为Web应用程序提供移动支持.我的应用程序中有一个要求,即下拉屏幕刷新页面以获取最新更新.我在iPhone原生应用程序中看到了这个功能,它也在twitter和foursquare移动网站上实现.

我在这里看过一些帖子,但我无法理解他们到底在说什么......我对这个环境很新.请指导我做这个功能.

这个功能有没有javascript库或jqueries？

Answer 1

从本质上讲,pull to refresh仅使用被劫持的javascript滚动机制(如iScroll)公开实现.这就是Twitter如何做到这一点 - 使用某种js webkit css3滚动库.但是,即使在iPhone 4上,你也会注意到,推特在移动网络中的滚动很简陋而不是100%自然.

昨天,我写了一个滚动来刷新overflow: scroll组件的处理程序.现在iPhone正在支持overflow: scroll,我们不必再劫持滚动了.当Apple修复当前的iOS -webkit-overflow-scrolling时,尤其如此:touch bug.

我还不能提供我的代码开源,但是这里有一些注释的界面.

(function(window, $, undefined) {

var hasTouch = 'ontouchstart' in window,
    startEvent = hasTouch ? 'touchstart' : 'mousedown',
    endEvent = hasTouch ? 'touchend' : 'mouseup';

var STATES = {
   ...
};

var CLASS_NAMES = {
   ...
};

var PullToReload = function(callback, wrapper, instructionsContent) {
// create all the dom elements and append the right before a content wrapper, but after a primary main wrapper.
// <div class="mainWrapper" style="overflow: scroll; height: 600px;"><div class="pullToReloadWrapper"></div><div class="contentWrapper"></div></div> is the markup.

// Check if the main wrapper's height is bigger than the content wrapper's height. If so, then change the main wrapper height to be the height of the content wrapper.

// scroll main wrapper by the reload wrapper's height.

// set state to pull

// invoke initEvents()
};

PullToReload.prototype.setState = function(state) {
// set the state of either pull, update, or release. Change CSS classes and content.
}
// boiler plate event handling switch
PullToReload.prototype.handleEvent = function(e) {
    switch (e.type) {
    case startEvent:
        this.start(e);
        break;
    case "scroll": 
        this.scroll(e);
        break;
    case endEvent:
        this.end(e);
        break;
    }
};

PullToReload.prototype.initEvents = function() {
// add event listeners for startEvent and endEvent with method "this"
// calling this in an event listener automatically calls handleEvent()

};

PullToReload.prototype.start = function() {
    // start listening to on scroll for the wrapper
};

PullToReload.prototype.end = function(e) {
// remove scroll event listener
// if the current state is in release, then set state to update and invoke the callback,
// else the state is in pull, then invoke reset()

};

PullToReload.prototype.scroll = function(e) {
// if current scroll position is almost to the top, change state to release.
// else put it back to pull state.

};

PullToReload.prototype.reset = function() {       
// animate scroll to height of reload component. 
// put css classes back to the beginning 
};
})(window, jQuery, I);

此解决方案适用于iOS5,Safari,Chrome以及其他可能的解决方案.我不得不在几个地方使用jQuery,主要是动画滚动.

这个解决方案不需要css3滚动处理程序,只是 overflow: scroll;

Answer 2

首先学习JavaScript,XHttpRequests,然后触摸事件.

刷新的提示只不过是XHR(AJAX)调用的触发器,它将新数据附加到您想要的所选元素上.

但如果您想要一个简短的答案,请查看Cubiq的iScroll 4,网址为http://cubiq.org/iscroll-4

最好的滚动JS.

以下是示例:http://cubiq.org/dropbox/iscroll4/examples/pull-to-refresh/