IOS: You must override the supportedEvents method Error thrown when supportedEvents is implemented in super class

[saumitrabhave]

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Environment

React Native Environment Info:
System:
OS: macOS High Sierra 10.13.6
CPU: x64 Intel(R) Core(TM) i5-4278U CPU @ 2.60GHz
Memory: 140.67 MB / 8.00 GB
Shell: 3.2.57 - /bin/bash
Binaries:
Node: 9.11.1 - /usr/local/bin/node
npm: 5.6.0 - /usr/local/bin/npm
Watchman: 4.9.0 - /usr/local/bin/watchman
SDKs:
iOS SDK:
Platforms: iOS 12.0, macOS 10.14, tvOS 12.0, watchOS 5.0
Android SDK:
Build Tools: 21.1.2, 23.0.1, 24.0.0, 24.0.1, 25.0.0, 25.0.2, 25.0.3, 26.0.1, 26.0.2, 26.0.3, 27.0.2, 27.0.3, 28.0.2
API Levels: 22, 23, 24, 25, 26, 27, 28
IDEs:
Android Studio: 3.2 AI-181.5540.7.32.5014246
Xcode: 10.0/10A255 - /usr/bin/xcodebuild
npmPackages:
react: ^16.5.0 => 16.5.0
react-native: ^0.57.1 => 0.57.1
npmGlobalPackages:
create-react-native-app: 1.0.0
react-native-cli: 2.0.1
react-native-create-library: 3.1.2
react-native-git-upgrade: 0.2.7
react-native-webengage: 1.0.3

Description

RCTEventEmitter has a check implemented in class initializer to check that the Implementation being created implements 'supportedEvents' method. this is achieved here

But the RCTClassOverridesInstanceMethod method defined here uses class_copyMethodList obj-C Runtime method to get instance methods and iterate over them to see if required method is implemented.

as per Apple Docs class_copyMethodList does NOT return instance methods implemented by super classes.

This causes the app to crash in Dev mode (because of RCTAssert?) if the app has its own hierarchy of RCTEventEmitters, in which case the supportedEvents is implemented by an intermediate superclass between the current class and RCTEventEmitter.

IMO, the implementation should walk the inheritance hierarchy till RCTEventEmitter to make the correct assertion.

Reproducible Demo

Create a Native Module with One BaseEmitter which extends from RCTEventEmitter implement all the required functionalities also the supportedEvents method. Now create another class MainEmitter which extends from BaseEmitter, do not implement the supportedEvents method in MyEmitter to re-use implementation from BaseEmitter

App will crash on first use of MainEmitter

Note: Its a copy of #20687 because I could not update it on time with latest react version.

[stale]

Hey there, it looks like there has been no activity on this issue recently. Has the issue been fixed, or does it still require the community's attention? This issue may be closed if no further activity occurs. You may also label this issue as "For Discussion" or "Good first issue" and I will leave it open. Thank you for your contributions.

[stale]

Closing this issue after a prolonged period of inactivity. If this issue is still present in the latest release, please feel free to create a new issue with up-to-date information.