[WXSDKEngine initSDKEnvironment]
//注册组件、模块、Handlers
|-[WXSDKEngine registerDefaults]
//1. 注册组件
|--[WXSDKEngine _registerDefaultComponents]
//2. 注册模块
|--[WXSDKEngine _registerDefaultModules]
//3. 注册Handler
|--[WXSDKEngine _registerDefaultHandlers]
//4. 加载JSFramework "native-bundle-main.js"
|-[WXBridgeManager executeJsFramework:]
//注册组件
|--[WXSDKEngine _registerDefaultComponents]
|---[WXSDKEngine registerComponent:withClass:withProperties:]
//注册组件-在Native里注册 WXComponentFactory._componentConfigs
|----[WXComponentFactory registerComponent:withClass:withPros:]
|-----[[WXComponentConfig alloc] initWithName:class:pros:]
|-----[WXComponentConfig registerMethods] // WX_EXPORT_METHOD 和 WX_EXPORT_METHOD_SYNC
|-----_componentConfigs { key: name, value: WXComponentConfig }
//注册模块
|--[WXSDKEngine _registerDefaultModules]
|---[WXSDKEngine registerModule:withClass:]
//注册模块-在Native里注册 WXModuleFactory._moduleMap
|----[WXModuleFactory registerModule:withClass:]
|-----[WXModuleConfig registerMethods]
//注册Handler
|--[WXSDKEngine _registerDefaultHandlers]
|---[WXSDKEngine registerHandler:withProtocol:]
//注册Handler-在Native里注册 WXHandlerFactory.handlers
|----[WXHandlerFactory registerHandler:withProtocol:]
//加载JSFramework "native-bundle-main.js"
|-[WXBridgeManager executeJsFramework:]
|--[WXBridgeContext executeJsFramework:]
|---[WXJSCoreBridge executeJsFramework:]
|----[JSContext evaluateScript:withSourceURL:]