Flexible size React Native views with Fabric on iOS

[BakkerTom]

I'm trying to embed a React Native view inside a UIKit view hierarchy, where the React Native view should automatically adapt its size based on its content.

I'm using the RCTRootViewFactory to create the view via view(withModuleName:). This returns an instance of RCTSurfaceHostingProxyRootView, which is meant to behave like a drop-in replacement for RCTRootView.

According to the current React Native docs, you can set the sizeFlexibility and delegate properties to get notified when the view’s intrinsic size changes. However, in my case—under the New Architecture and Fabric—the delegate method never gets called.

Finding: RCTFabricSurface vs. RCTSurface

Digging into the implementation, I noticed that RCTSurfaceHostingProxyRootView (under Fabric) internally uses RCTFabricSurface. Unlike RCTSurface, RCTFabricSurface does not call the delegate methods that notify about intrinsic size changes.

This is confusing, because the official guidance seems to assume that behavior is still supported. So my questions are:

• Is this a bug?
• Is there a supported way to have React Native views under Fabric dynamically size to fit their content?
• Is this behavior intentionally not supported in Fabric?
• If not, is there a workaround or future support planned?

Any insight would be greatly appreciated!

[hoanghuy-ng]

i got same behavior. it's bug ?