1. 界面布局
1.1. iOS
1.1.1. RCTShadowView
和 yogaNode 建议映射
1.1.2. RCTUImanager
把 yoga 计算的布局结果同步到原生界面
RCTUImanager: setNeedsLayout > _layoutAndMount > [self addUIBlock:[self uiBlockWithLayoutUpdateForRootView:rootView]] > flushUIBlocksWithCompletion
1.1.3. RCTUIManagerObserver
渲染生命周期监听