Unsupported top level event type "topLoadingStart" dispatched in Custom WebView

Is this a bug report?

I believe so.

Have you read the Contributing Guidelines?

Yes.

Environment

Environment: OS: macOS Sierra 10.12.6 Node: 8.7.0 Yarn: 1.2.1 npm: 5.4.2 Watchman: 4.7.0 Xcode: Xcode 9.1 Build version 9B55 Android Studio: 2.3 AI-162.4069837

Packages: (wanted => installed) react: 16.0.0 => 16.0.0 react-native: 0.50.3 => 0.50.3

Target Platform: iOS (11.1)

Steps to Reproduce

We implemented a Custom WebView. It used to work in RN 0.49 (we were using the components/WebView.ios.js from master). I’m not an Objective-C developer and probably I’m doing something wrong. Our implementation looks like this:

// RCTCustomWebViewManager.h
#import <React/RCTWebViewManager.h>
#import <React/RCTWebView.h>

@interface RCTCustomWebViewManager : RCTWebViewManager

@end


// RCTCustomWebViewManager.m
#import "RCTCustomWebViewManager.h"

@interface RCTCustomWebViewManager () <RCTWebViewDelegate>

@end

@implementation RCTCustomWebViewManager { }
RCT_EXPORT_MODULE()
RCT_REMAP_VIEW_PROPERTY(keyboardDisplayRequiresUserAction, _webView.keyboardDisplayRequiresUserAction, BOOL)

- (UIView *)view
{
  RCTWebView *webView = [RCTWebView new];
  webView.delegate = self;
  return webView;
}

@end

Expected Behavior

I expect it works.

Actual Behavior

Reproducible Demo

https://github.com/juangl/with-custom-webview

[cbrevik]

Seems related to how events are resolved in requireNativeComponent.js

Spent a bit of time investigating this, and was about to submit a PR, but seems like @shergin already fixed this in master: https://github.com/facebook/react-native/commit/2afe7d4765ffc0d0c71d233211edd1d21972040e

So it will probably be working again in a future version of RN 👍

Edit: The reason why topLoadingStart was not referenced in the iOS code is because there’s a name-normalization method for events for iOS: https://github.com/facebook/react-native/blob/d2c569795ca07b6b7c0227cfc6d0b3bf5dd23b99/React/Base/RCTEventDispatcher.m#L20 Bit hacky, and makes debugging more difficult, but oh well. Yet another gotcha 😃

[cbrevik]

Quickly tested it out, and was able to reproduce the same error.

Regarding:

You’ll have to duplicate RCTWebViewManager.m, since the exported macro-defined methods/properties (with RCT_REMAP_VIEW_PROPERTY, RCT_EXPORT_METHOD, etc) are only picked up from the subclass, and not from the parent.

This should not be the case any more. With #14775 inheritance works on iOS as well.

I am not sure where the topLoadingStart event is coming from though. Searching through the code base I only find references in Android-code. Might be something changed with events on iOS from RN 0.49 -> 0.50.

Maybe @javache knows?