title: I can't run react-native-webrtc-demo on my android emulator in mac os
body: <p>I am going to show IP camera real-time on the mobile app.</p>
  
  <p>So I downloaded Oney's RCTWebRTCDemo from GitHub to run it.</p>
  
  <p>I did the following works.</p>
  
  <pre><code>Bians-iMac:MyHome byz$ git clone https://github.com/oney/RCTWebRTCDemo.git
  Cloning into 'RCTWebRTCDemo'...
  remote: Counting objects: 359, done.
  remote: Total 359 (delta 0), reused 0 (delta 0), pack-reused 359
  Receiving objects: 100% (359/359), 456.78 KiB | 303.00 KiB/s, done.
  Resolving deltas: 100% (155/155), done.
  Bians-iMac:MyHome byz$ cd RCTWebRTCDemo
  Bians-iMac:RCTWebRTCDemo byz$ npm install
  npm WARN deprecated connect@2.30.2: connect 2.x series is deprecated
  npm WARN deprecated gulp-util@3.0.8: gulp-util is deprecated - replace it, following the guidelines at https://medium.com/gulpjs/gulp-util-ca3b1f9f9ac5
  npm notice created a lockfile as package-lock.json. You should commit this file.
  added 592 packages from 409 contributors and audited 5796 packages in 434.447s
  found 24 vulnerabilities (13 low, 3 moderate, 8 high)
    run `npm audit fix` to fix them, or `npm audit` for details
  Bians-iMac:RCTWebRTCDemo byz$ npm audit fix
  
  &gt; fsevents@1.2.4 install /Volumes/STUDY/Work/MyHome/RCTWebRTCDemo/node_modules/fsevents
  &gt; node install
  
  [fsevents] Success: "/Volumes/STUDY/Work/MyHome/RCTWebRTCDemo/node_modules/fsevents/lib/binding/Release/node-v57-darwin-x64/fse.node" already installed
  Pass --update-binary to reinstall or --build-from-source to recompile
  npm WARN react-native@0.56.0 requires a peer of react@16.4.1 but none is installed. You must install peer dependencies yourself.
  
  + react-native@0.56.0
  added 407 packages from 157 contributors, removed 196 packages, updated 72 packages and moved 3 packages in 59.949s
  fixed 20 of 24 vulnerabilities in 5796 scanned packages
    1 package update for 4 vulns involved breaking changes
    (use `npm audit fix --force` to install breaking changes; or refer to `npm audit` for steps to fix these manually)
  Bians-iMac:RCTWebRTCDemo byz$ react-native link
  Scanning folders for symlinks in /Volumes/STUDY/Work/MyHome/RCTWebRTCDemo/node_modules (9ms)
  rnpm-install info Platform 'ios' module react-native-webrtc is already linked 
  rnpm-install info Linking react-native-webrtc android dependency 
  rnpm-install info Platform 'android' module react-native-webrtc has been successfully linked 
  Bians-iMac:RCTWebRTCDemo byz$ react-native run-android
  Scanning folders for symlinks in /Volumes/STUDY/Work/MyHome/RCTWebRTCDemo/node_modules (11ms)
  JS server already running.
  Building and installing the app on the device (cd android &amp;&amp; ./gradlew installDebug)...
  File /Users/byz/.android/repositories.cfg could not be loaded.
  
  FAILURE: Build failed with an exception.
  
  * What went wrong:
  A problem occurred configuring project ':WebRTCModule'.
  &gt; Could not resolve all dependencies for configuration ':WebRTCModule:_debugPublishCopy'.
     &gt; Could not find com.android.support:appcompat-v7:26.1.0.
       Searched in the following locations:
           file:/Users/byz/Library/Android/sdk/extras/android/m2repository/com/android/support/appcompat-v7/26.1.0/appcompat-v7-26.1.0.pom
           file:/Users/byz/Library/Android/sdk/extras/android/m2repository/com/android/support/appcompat-v7/26.1.0/appcompat-v7-26.1.0.jar
           file:/Volumes/STUDY/Work/MyHome/RCTWebRTCDemo/android/sdk-manager/com/android/support/appcompat-v7/26.1.0/appcompat-v7-26.1.0.jar
       Required by:
           RCTWebRTCDemo:WebRTCModule:unspecified &gt; com.facebook.react:react-native:0.56.0
  
  * Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
  
  BUILD FAILED
  
  Total time: 13.627 secs
  Could not install the app on the device, read the error above for details.
  Make sure you have an Android emulator running or a device connected and have
  set up your Android development environment:
  https://facebook.github.io/react-native/docs/getting-started.html
  </code></pre>
  
  <blockquote>
    <p>Operating System: mac OS HighSierra 10.13.5 </p>
    
    <p>Android SDK: 23.0.2 &amp; 26 installed.</p>
  </blockquote>
  
  <p>Can anyone tell me how to fix this?</p>
  
  <p>Thanks for your attention.</p>