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React Native has a native Camera component billed as

"The comprehensive camera module for React Native. Including photographs, videos, and barcode scanning!"
Sounds cool, and the installation looks to be easy going by the instructions at
https://github.com/react-native-community/react-native-camera

Note: This guide assumes you have already built a basic react native app using
> create-react-native-app dev-app-01
or whatever cooler name you gave your app
and you want to add camera functionality to prototype an app

And you have set up your node js, react native, android sdk environment, and ejected your react native app; if not you can follow the guide Eject your react native app!

And the adventure begins:

> npm install react-native-camera --save

That should work
> react-native link react-native-camera

Try running it
> react-native run-android

And the first
Error #1
File C:\Users\[username]\.android\repositories.cfg could not be loaded.

To confirm that the automatic install and link methods did the right things,read over the manual instructions to install on android (repeated below)
https://github.com/react-native-community/react-native-camera#android

Note: I had to perform steps 5 and 6; Steps 1 through 4 were done by the link command

1. > npm install react-native-camera --save
2. Open up `android/app/src/main/java/[...]/MainApplication.java   
    Add import com.lwansbrough.RCTCamera.RCTCameraPackage; to the imports at the top of the file
    Add new RCTCameraPackage() to the list returned by the getPackages() method.
    Add a comma to the previous item if there's already something there.
3. Append the following lines to android/settings.gradle:   
    include ':react-native-camera'
    project(':react-native-camera').projectDir = new File(rootProject.projectDir, '../node_modules/react-native-camera/android')
4. Insert the following lines inside the dependencies block in android/app/build.gradle:    c
   ompile project(':react-native-camera')
5. Declare the permissions in your Android Manifest (required for video recording feature)   
    <uses-permission android:name="android.permission.RECORD_AUDIO"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
6. Add jitpack to android/build.gradle
    allprojects {
        repositories {
            maven { url "https://jitpack.io" }
        }
     }

Try running  again
> react-native run-android

And the same Error #1
File C:\Users\[username]\.android\repositories.cfg could not be loaded.

So create an empty file C:\Users\[username]\.android\repositories.cfg

Note: Make sure you already have the android emulator running
Open Android StudioTools -> Android -> ADV Manager aka Android Virtual Device -> Start

Try running  again
> react-native run-android

And Error #2
> Could not resolve all dependencies for configuration ':app:_debugApkCopy'.   
> Could not find com.android.support:exifinterface:26.0.2.

Manually add the dependencies to add the missing libs
Browse to c:\Dev\ReactNativeApps\dev-app-01\android\app\build.gradle
And add the dependencies
dependencies {   
    compile 'com.android.support:exifinterface:26.0.2'
  
    compile "com.android.support:support-v4:26.0.1"
  
    compile fileTree(dir: "libs", include: ["*.jar"])
  
    compile "com.android.support:appcompat-v7:23.0.1"
  
    compile "com.facebook.react:react-native:+"  
  
    compile project(':react-native-camera')
}

To add it
Open Android StudioTools -> Android -> SDK Manager
Ensure the latest android versions are enabled, and save

Try running  again
> react-native run-android

And again Error #2

You can also delete the gradle cache which may be stale from the manual android instructions above
Navigate toC:\Users\[username]\.gradle\caches
And delete all folders

Note: Gradle is a build system used by Google for androidGradle is similar in concept to Maven, Composer, Npm, Make, etc

Try running  again
> react-native run-android

React native via gradle will re-download all the required java packages that are set in the build.gradle
And again Error #2

Well, let’s look at the build.gradle file on GitHub for the camera project
https://github.com/react-native-community/react-native-camera/blob/master/android/build.gradle

Ok, the repositories and dependencies sections are different from the main documentation.
Let’s try them
repositories {  
 mavenCentral()
 
 maven {
 url 'https://maven.google.com'  }  
 maven { url "https://jitpack.io" }
}
dependencies {  
 compile 'com.facebook.react:react-native:+'
 compile "com.google.zxing:core:3.2.1"
 compile "com.drewnoakes:metadata-extractor:2.9.1"
 compile 'com.google.android.gms:play-services-vision:+'
 compile "com.android.support:exifinterface:26.0.2"
 compile 'com.github.react-native-community:cameraview:df60b07573'
}


Try running  again
> react-native run-android

And Error #3
> Manifest merger failed :
Attribute meta-data#android.support.VERSION@value value=(26.0.2) from [com.android.support:exifinterface:26.0.2] AndroidManifest.xml:25:13-35
is also present at [com.android.support:support-v4:26.0.1] AndroidManifest.xml:28:13-35 value=(26.0.1).
Suggestion: add 'tools:replace="android:value"' to <meta-data> element at AndroidManifest.xml:23:9-25:38
to override.

Going by the Q&A section of the documentation
https://github.com/react-native-community/react-native-camera#q--a

Comment out the dependency   
compile 'com.google.android.gms:play-services-vision:+'

Try running  again
> react-native run-android

And Error #4
Error: Cannot create directory C:\Dev\ReactNativeApps\DevApp02\android\app\build\intermediates\incremental\mergeDebugResources\merged.dir\values

Perhaps this exceeds window directory length
So navigate there and create it manually
C:\Dev\ReactNativeApps\DevApp02\android\app\build\intermediates\incremental\mergeDebugResources\merged.dir
Values

Try running  again
> react-native run-android

And again Error #4

So try deleting the build folder
C:\Dev\ReactNativeApps\DevApp02\android\app\build\

Hmm .. back to Error #3

Going by the Q&A section of the documentation
https://github.com/react-native-community/react-native-camera#q--a

exclude group: "com.android.support"And force exifinterface:26.0.2
repositories {
  mavenCentral()

  maven { url 'https://maven.google.com' }

  maven { url "https://jitpack.io" }
}
dependencies {
  compile "com.android.support:appcompat-v7:23.0.1"
  compile 'com.facebook.react:react-native:+'
  compile "com.google.zxing:core:3.2.1"
  compile "com.drewnoakes:metadata-extractor:2.9.1"
  compile ('com.android.support:exifinterface:26.0.2') {       force = true;   }   compile (project(':react-native-camera')) {
      exclude group: "com.android.support"   
  }

  compile fileTree(dir: "libs", include: ["*.jar"])
}


Try running  again
> react-native run-android

Well, no console errors
So try to launch the basic default app .. and that now works again

Optimistic -sign-

Add the camera example code from the main doc
https://github.com/react-native-community/react-native-camera#usage

Try running again
> react-native run-android

And Error #5

The react native red screen

Instead of trying to debug that, let’s try using the example app checked into GitHub
https://github.com/react-native-community/react-native-camera/blob/master/RNCameraExample/App.js

Try running  again
> react-native run-android

And Error #6
bundling failed: Error: Unable to resolve module `./assets/ic_photo_camera_36pt.png`


So browse the GitHub project, and there is an assets/ directory
Copy all those to your project
It is easier to git clone the project or download it as a zip and copy the assets/ folder over
https://github.com/react-native-community/react-native-camera


Try running  again
> react-native run-android

And Error #7
cannot load index.android.js

Per a git issue thread
https://github.com/facebook/react-native/issues/15388
adb reverse tcp:8081 tcp:8081

Adb was not in my path, so I had to
C:\Users\[username[\AppData\Local\Android\sdk\platform-tools\adb reverse tcp:8081 tcp:8081

Try running  again
> react-native run-android

And Error #8
A white screen

Trying another option in the git issue thread
https://github.com/facebook/react-native/issues/15388#issuecomment-356937491

Shake the phone -sign- to show developer options for react native
Choose Dev Settings
Tap Debug server host and port for device
Enter your laptops IP and port 8081

Note: You can get your IP from the command prompt
> ipconfig

Try running  again
> react-native run-android


And hey, it actually works.
Cool.

There was a lot of environment initialization and fixing from the joys of rapid development libraries and multiple complex build tools, but at least the camera api is available and -currently- works.

Now to actually designing an app.
Till next time.

End of document. Thanks for reading.