How and what does npm link do in this example? - react-native

I'm installing react-native-elements and in the installation guide there is this command:
npm i react-native-vector-icons --save && react-native link react-native-vector-icons
I am curious what this part of the command does and why it is necessary: react-native link react-native-vector-icons

As you might know, React Native allows you to interface with the native APIs of the OS via JavaScript. In order to establish this interface, some configuration is required in the native side (linking libraries, adding search paths and assets...), and since this process is relatively repetitive and can be automated, the RN folks made the link command in order to set up modules with native code more easily. In the case of React Native Vector Icons, it will add the font files and other configuration to your project, for both Android and iOS.

Related

Can i use native base without installing `react-native link`?

I want to use native-base but i do not want to install react-native link. How can i do this?
The reason i do not want to install react-native link is because react-native doc suggest us to delete react-native CLI globally.
I guess you have misunderstanding of what react-native link does. react-native link is an automatic way for installing native dependencies. read more here
In case of Native Base. This library is consist of other npm packages, so you need to install them in order to work properly with Native Base.
Native Base Docs states
Install Peer Dependencies
The peer dependencies included from any npm packages does not automatically get installed. Your application will not depend on it explicitly. read more here
If your react-native version is 0.60+ you do not need to link dependencies. All you need to do is install dependencies and you are good to do.

React Native Video

i'm trying to use 'react-native-video' in my application, i have used the following lines to get it:
npm install --save react-native-video
react-native link react-native-video (since my react native version is 0.59)
after doing so and using "Video" component from 'react-native-vide' i got an error like below:
what is the problem? what can i do? any ideas?
You did not link the library properly.
After having installed the library through npm i --save react-native-video, you'll need to run react-native link react-native-video in order to link it. This may or may not work - if it does not, you'll need to link manually according to the installation instructions of the library.
You might be using CocoaPods in which case you'll need to run these commands as well: cd ios && pod install
If you receive an error, you're most likely not using CocoaPods and this is the wrong approach.
Please note that you'll need to reinstall the app on the phone / simulator afterwards since you've changed the native dependencies. You'll also need to do this if you're using (ejected) Expo or anything alike. If you're using Expo with the managed workflow (= not ejected) you're not able to use libraries that depend on native linking.

Problem with new upgraded version(0.60) of react native when we linking any third party module

In my cases when i link third party module in react native like..
npm install react-native-vector-icons --save.
react-native link
It gives message for me....
React Native CLI uses autolinking for native dependencies, but the following modules are linked manually:-
react-native-vector-icons (to unlink run: "react-native unlink react-native-vector-icons")
but if i am not link the module it will not work for me
this problem occurs only in react-native new upgraded version(0.60) not for older version.
please suggest me any solution for the given problem.
Always make sure to install any third party library manually rather than doing react-native link.
Follow the detailed manual installation https://github.com/oblador/react-native-vector-icons from here.
Firstly run this command react-native unlink react-native-vector-icons
After unlink is successful, follow the manual installation steps.
Also it's better to use yarn (https://yarnpkg.com/en/) over npm while installing a package.
Hope this helps!
Since react native 0.60 auto-linking is avaliable so that means that future libraries release won't need to run the "link" command. If you're using vector-icons you'll need to wait until the upgrade. You can use the vector icons linked to you project normally, but be careful because that will not be compatible in the next major release in react native. I also tried to upgrade to react native 0.60.3, but this is not the great idea if your using a lot of dependencies.

When to use react-native link?

I understand that react-native link (see post) is an automatic way to install native dependencies. The post above explain how to use the link command but lacking the detail of when to use it. Should it be used after adding a component, every code change or after introducing new module to the app?
Why we use react-native-link??
In this post, I will explain why we use react native link command and when we need to use this command or not?
First, we will understand what is native module??
Native Modules
Native modules are usually distributed as npm packages, apart from the typical javascript files and resources they will contain an Android and ios library project. 
React Native provides an impressive amount of native modules that give you direct access to core platform APIs on both Android and IOS.
For example react-native-maps, react-native-firebase, react-native-socketio etc.
These modules or packages contained both platform (Android and Ios) code.
Now coming on to the react native link
Those libraries which are use native code, in that case you'll have to add these files to your app. For linking those library with react native code need to run react-native-link
Here are the few steps to link your libraries that contain native code
Automatic linking
Step 1
Install a library with native dependencies:
$ npm install --save
Step 2
Link your native dependencies:
$ react-native link
Done! All libraries with native dependencies should be successfully linked to your iOS/Android project.
Where we don't use react-native-link??
Those components which are only written in javascript they are not using any native code (Android and Ios). There is no need to run react-native-link.
For example rn-modal-picker, react-native-check-box etc.
You should check out this other answer: The use of react-native-link command?
You only need to run react-native link NAME_OF_PACKAGE when you install a new package that has a native codebase, or without arguments if you want to do it for multiple of them.

What is react-native link?

What is the purpose of the react-native link command?
Note: from React-Native 0.60.0 linking packages using react-native link has become redundant. Autolink has been added to the React-Native CLI which means that iOS will now use cocoapods and Android will use gradle. You can read more about Autolinking here.
What is react-native link?
react-native link is an automatic way for installing native dependencies. It is an alternative to manually linking the dependency in your project. It works for both Android and iOS.
When linking a project manually the majority of the steps are the same and so using react-native link allows you to install the native dependency with less fuss and without having to type similar code or perform similar actions repeatedly.
However, it should be noted that running react-native link will not always link a package fully, sometimes additional steps are required and you should check carefully with the installation instructions.
Always read the instructions carefully before installing a dependency and linking it.
iOS Considerations
If your project is using CocoaPods and the dependency that you are linking has a .podspec then when you use run react-native link it will update your Podfile. This is instead of adding the files directly to your Xcode project. You will also have to run pod install inside your ios directory otherwise the native dependency won't be fully installed.
Sometimes installing using CocoaPods can cause more issues, and not every dependency needs to be installed with CocoaPods you could always follow the steps that I outlined in this SO answer to stop react-native link adding a dependency to the Podfile, it is not ideal but it is a workaround. Some dependencies require additions to be made to the Podfile, so you should only do this if the dependency doesn't require pods to run.
react-native link or react-native link dependency-name
Should you just use react-native link when linking any dependency or should you be more explicit and use react-native link dependency-name?
From my experience it is better to use react-native link dependency-name. This is due to the fact that react-native link will try to link (or re-link) all the dependencies that can be linked and this can lead to code duplication. Most of the issues that I have experienced have been when the Android native dependency is being linked. I think there has been some headway in stopping this from happening in subsequent updates, but the old adage applies here once bitten, twice shy
Linking good practice
When using react-native link dependency-name you should follow good practice so that you don't get stung. Sometimes dependencies that you try don't work as expected and removing all the code that was added during the linking process can be tricky. (Xcode project files can be a nightmare to go through if you are unfamiliar with them).
This is how I install dependencies and then link them.
Make sure that you are using version control, like git.
Make sure your code is fully committed with no unsaved changes.
Create a new branch, and check it out.
Install your dependency npm i dependency-name
Then link you dependency react-native link dependency-name
Perform any additional installation steps that the dependency requires. See the installation instructions for the dependency.
Check that your code works with the new dependency.
commmit changes and merge the branch.
Manual Linking
If you prefer to link your native dependencies manually then you should either follow the instructions on the dependency's website or you can look at the documentation that react-native provides.
Currently there is only an explanation on how to manually link iOS projects.
Manually linking Android requires you to make changes in the following locations:
settings.gradle
app/build.gradle
MainApplication.java
As always for the exact changes that you should make you should look at the dependency's manual linking instructions.
Do I have to link?
It depends on the dependency that you are using some dependencies use only code written in Javascript, so it is not required to link them, and there is no benefit served by running react-native link dependency-name.
However, if the dependency contains native code then you will have to link. Either manually or by using react-native link dependency-name.
How can I tell if I need to link the dependency?
Firstly you need to check the website, the github repo, or the npmjs.com page for the dependency. There will usually be instructions there telling you whether to link the dependency after you have installed it.
If you cannot find any instructions about linking, you (probably) won't need to link it.
If you are still unsure, check with the dependency maintainer.
Can I just run link anyway?
Yes, you can it won't do anything if there is nothing to link. But always run it with react-native link dependency-name to avoid issues.
When do I run link?
You only run it after you have installed your dependency. I would recommend running it just after you have installed the dependency. You should then check to make sure that it works, before installing any new dependencies so that you can easily debug.
You shouldn't need to run it more than once per dependency.
It doesn't matter how many components or changes to the javascript code that you make it won't affect the linking, as the linking is purely native and components are javascript.
What is autolink?
Autolink is a new feature that is being added to the react-native-cli. You can read more about autolink here.
Autolink replaces react-native-link
Autolinking is a mechanism built into CLI that allows adding a
dependency with native components for React Native to be as simple as:
yarn add react-native-webview
Autolinking is a replacement for react-native link that brings new features (such as ability to easily integrate native dependencies on iOS) and fixes some of the long-standing issues.
Once it is fully implemented it should make adding dependencies with native-code to your project much easier.
Linking native library means that you are going to integrate already implemented module into your application or module which completes your react native's module functionality.
Steps to integrate lib(android):
1) Add package name to new packages() 2) Add dependencies to settings.gradle file and main application's gradle i.e app/gradle file. 3) sync the projects gradle because you made changes in the gradle and it's done.
All manual steps like below you have to perform
1) Go to your project's home dir using cmd.
2) run npm install
3) Thereafter run rnpm link or react-native link
4) see ios folder in your project folder and if you find any pod file then run pod install after navigating into ios folder in cmd.
now instead,
1) Go to your project's home dir using cmd.
2) run npm install
3) Thereafter run rnpm link or react-native link
4) see ios folder in your project folder and if you find any pod file then run pod install after navigating into ios folder in cmd.
When you've installed a library with native content(android or ios) then you need to require linking to the component react-native library.
like this
react-native link react-native-sound-player
When you installed any third party library with native content,you have to link the dependencies in android and ios. react-native link is responsible for including the dependencies in gradlew and pod files.
for suppose you installed react-native-vector-icons package then you have to link in your gradlew files. the new version of react native 0.60 has auto linking.
npm install react-native-vector-icons
react-native link react-native-vector-icons
Thanks for asking this question
if you are working with fonts
react-native link is used for linking the fonts and assets to project
link command is also for linking the libraries to react-native
But now React-native too better so there is no need to link the library
we can use
pos install
npx jetify
it will automatically link the libraries
react-native link is an automatic way for installing native dependencies. It is an alternative to manually linking the dependency in your project. It works for both Android and iOS