usesCleartextTraffic, Enable react-native-debugger and `npm start` (Metro server) to work post API 27

[sanjarcode]

To enable usesCleartextTraffic=true only for non-release environments, you can use a Gradle-based approach with manifest placeholders. Here's how to do it:

1. Define a placeholder in AndroidManifest.xml:

   In your AndroidManifest.xml, update the usesCleartextTraffic attribute with a placeholder:

   <application
       android:usesCleartextTraffic="${usesCleartextTraffic}">
   </application>

2. Configure the placeholder in build.gradle:

   In your app/build.gradle, you can specify the placeholder value based on the build type (e.g., debug or release):

   android {
       ...
       buildTypes {
           debug {
               manifestPlaceholders = [usesCleartextTraffic: true] // Enable cleartext traffic for debug
           }
           release {
               manifestPlaceholders = [usesCleartextTraffic: false] // Disable cleartext traffic for release
           }
       }
   }

This will set usesCleartextTraffic to true for non-release builds like debug and false for release builds. You can adjust the values based on the environments you want.

By default npm start + npm run android runs in debug mode.

• ios is unaffected, since it has always been HTTPS.

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Without this the debug tool and Metro server, neither work. Like first upload is done and r key has no effect in Metro

[vsheyanov]

While looking for something related to RN, I found your issue. Exactly what I needed =) Thanks!