Summary:
Xcode 9 has compiler settings that are more strict. This can occur if someone updates there project to use the default settings.
This patch declares the default type instead of allowing the compiler to determine it. Instead of () we now say (void) in a block call.
Motivation
It was just trying to get my project totally empty of warnings, and it has no side effects. If there are side effects, then we should fix the type and not go with empty to represent void.
Test Plan
Update project settings in Xcode. This code doesn't have any known side effects since the compiler assumes the type is void when not declared.
Release Notes
[DOCS] - Fixed potential compiler build issue on Xcode 9 after updating settings in project.
Pull Request resolved: https://github.com/facebook/react-native/pull/17872
Differential Revision: D6981435
Pulled By: hramos
fbshipit-source-id: 508ecea0f8874dc16a25f1dee6255481b309f8c2
a93db4915b