新闻资讯APP开发流程（三） app.js

 如果注释里写的一样，我们将使用单window程序模板，

 在app.js里我们主要做几件事情：

-引导程序并载入我们需要的数据

-检测程序运行的设备类型，平台版本或网络连接

-载入并打开顶层的UI组件

 我们为android、iphone、ipad平台做判断，根据相应的平台载入相应的程序模板。

而事实上，因为校长追求平台UI的统一性，其实以上操作是多余的，也可以不用，因为所有的UI都是共用的，我们将全程使用view组件，view组件相当于web开发中的div层，所以这样做的结果就是所有平台的UI都是一样的，而且自定义UI样式非常方便，比如说，如果底部使用传统的tabGroup，那么在titanium中你会发现，tab样式是非常难改变的。

并且titanium最佳实践里提到我们尽可能使用单上下文。

app.js

/*
 * Single Window Application Template:
 * A basic starting point for your application.  Mostly a blank canvas.
 * 
 * In app.js, we generally take care of a few things:
 * - Bootstrap the application with any data we need
 * - Check for dependencies like device type, platform version or network connection
 * - Require and open our top-level UI component
 *  
 */

//bootstrap and check dependencies
if (Ti.version < 1.8 ) {
    alert('Sorry - this application template requires Titanium Mobile SDK 1.8 or later');          
}

// This is a single context application with mutliple windows in a stack
(function() {
    //determine platform and form factor and render approproate components
    var osname = Ti.Platform.osname,
        version = Ti.Platform.version,
        height = Ti.Platform.displayCaps.platformHeight,
        width = Ti.Platform.displayCaps.platformWidth;
    
    //considering tablet to have one dimension over 900px - this is imperfect, so you should feel free to decide
    //yourself what you consider a tablet form factor for android
    var isTablet = osname === 'ipad' || (osname === 'android' && (width > 899 || height > 899));
    
    var Window;
    if (isTablet) {
        Window = require('ui/tablet/ApplicationWindow');
    }
    else {
        // Android uses platform-specific properties to create windows.
        // All other platforms follow a similar UI pattern.
        if (osname === 'android') {
            Window = require('ui/handheld/android/ApplicationWindow');
        }
        else {
            Window = require('ui/handheld/ApplicationWindow');
        }
    }
    new Window().open();
})();