Avoid using absolute path for podspec for version control

[jpolo]

Environment

System:
OS: macOS 10.14.5
CPU: (8) x64 Intel(R) Core(TM) i7-7920HQ CPU @ 3.10GHz
Memory: 88.32 MB / 16.00 GB
Shell: 5.3 - /bin/zsh
Binaries:
Node: 8.11.3 - /var/folders/78/3_1gd4qx1gj_qtw62hhywmtm0000gn/T/yarn--1562337540193-0.22427215859470917/node
Yarn: 1.16.0 - /var/folders/78/3_1gd4qx1gj_qtw62hhywmtm0000gn/T/yarn--1562337540193-0.22427215859470917/yarn
npm: 6.9.0 - ~/.nvm/versions/node/v8.11.3/bin/npm
Watchman: 4.9.0 - /usr/local/bin/watchman
SDKs:
iOS SDK:
Platforms: iOS 12.2, macOS 10.14, tvOS 12.2, watchOS 5.2
Android SDK:
API Levels: 23, 25, 26, 27, 28
Build Tools: 26.0.0, 26.0.1, 26.0.3, 27.0.3, 28.0.3
System Images: android-25 | Google APIs Intel x86 Atom, android-25 | Google Play Intel x86 Atom
IDEs:
Android Studio: 3.4 AI-183.6156.11.34.5522156
Xcode: 10.2.1/10E1001 - /usr/bin/xcodebuild
npmPackages:
@react-native-community/cli: ^2.1.0 => 2.1.0
react: 16.8.6 => 16.8.6
react-native: 0.59.9 => 0.59.9
npmGlobalPackages:
react-native-cli: 2.0.1

Description

The pod lock file created by iOS autolinking saves absolute file references (ex: /Users/MyUser/MyProject/node_modules/react-native-lib)

Using relative paths to the root is better because they are portable and versionable ( the example should be ../node_modules/react-native-lib)

Reproducible Demo

[thymikee]

Would you like to send a PR with this improvement? :) We'll need to make changes to this file: https://github.com/react-native-community/cli/blob/master/packages/platform-ios/native_modules.rb

[jpolo]

I have to confess that I am not quite fluent in Ruby language.
I'll wait a few days and if nobody react to this issue for help, I'll try and tinker a fix.

[simka]

if this one's not taken, I'd be happy to try ;)

[jpolo]

Thanks @maciejsimka ! I looked at your solution to learn some Ruby.
As I understand the code does not seems portable to systems with folder separator than Unix (i.e. Windows).
Is that a problem ? (The real question behind that, is does react native cli officially supports Windows?)

[thymikee]

@jpolo iOS project is only available for development on macOS, so no Windows there. Windows is supported by the CLI. We're working on making sure we don't break things there, but it can take some time. If you'd like to help: #471

[jpolo]

@thymikee You're right, the ruby part is only for iOS platform, so there is no problem...