Weex SDK初始化入口:[WXSDKEngine initSDKEnvironment]
Weex SDK初始化逻辑:
//注册组件、模块、Handlers
|-[WXSDKEngine registerDefaults]
//注册组件
|--[WXSDKEngine _registerDefaultComponents]
//注册模块
|--[WXSDKEngine _registerDefaultModules]
//注册Handler
|--[WXSDKEngine _registerDefaultHandlers]
//加载JSFramework "native-bundle-main.js"
|-[WXBridgeManager executeJsFramework:]