shrinkResources true

app/build.gradle

@@ -23,7 +23,8 @@ android {
 
     buildTypes {
         release {
-            minifyEnabled false
+            minifyEnabled true
+            shrinkResources true
             proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
         }
     }