diff --git a/.circleci/config.yml b/.circleci/config.yml
index 3f70ee4be544ed..b99eebf5ea33c5 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -170,7 +170,7 @@ android_defaults: &android_defaults
 macos_defaults: &macos_defaults
   <<: *defaults
   macos:
-    xcode: "10.2.0"
+    xcode: "10.1.0"
 
 # -------------------------
 #          JOBS
@@ -340,22 +340,12 @@ jobs:
   # Runs unit tests on iOS devices
   test_ios:
     <<: *macos_defaults
-    environment:
-      - REPORTS_DIR: "./reports"
     steps:
       - attach_workspace:
           at: ~/react-native
 
       - run:
-          name: Print Xcode environment
-          command: xcodebuild -version
-
-      - run:
-          name: List available devices
-          command: instruments -s devices
-
-      - run:
-          name: Boot iOS Simulator
+          name: Boot iPhone Simulator
           command: source scripts/.tests.env && xcrun simctl boot "$IOS_DEVICE" || true
 
       - restore-cache: *restore-brew-cache
@@ -367,91 +357,8 @@ jobs:
       - save-cache: *save-brew-cache
 
       - run:
-          name: Start Metro packager
-          command: yarn start --nonPersistent --max-workers=1 || echo "Can't start packager automatically"
-          background: true
-
-      - run:
-          name: Start WebSocket test server
-          command: open "./IntegrationTests/launchWebSocketServer.command" || echo "Can't start web socket server automatically"
-          background: true
-
-      - run:
-          name: Verify RNTester can be built
-          command: |
-            source ./scripts/.tests.env
-            xcodebuild \
-              -project RNTester/RNTester.xcodeproj \
-              -scheme RNTester \
-              -sdk iphonesimulator \
-              -destination "platform=iOS Simulator,name=$IOS_DEVICE,OS=$IOS_TARGET_OS" \
-              -UseModernBuildSystem=NO \
-              build | \
-            xcpretty --report junit --output "$REPORTS_DIR/junit/ios_buiild/results.xml" && \
-            exit "${PIPESTATUS[0]}"
-
-      - run:
-          name: Wait for Metro packager
-          command: |
-            max_attempts=60
-            attempt_num=1
-            until curl -s http://localhost:8081/status | grep "packager-status:running" -q; do
-              if (( attempt_num == max_attempts )); then
-                echo "Packager did not respond in time. No more attempts left."
-                exit 1
-              else
-                (( attempt_num++ ))
-                echo "Packager did not respond. Retrying for attempt number $attempt_num..."
-                sleep 1
-              fi
-            done
-            echo "Packager is ready!"
-
-      - run:
-          name: Preload the RNTesterApp bundles
-          command: |
-            curl --silent 'http://localhost:8081/RNTester/js/RNTesterApp.ios.bundle?platform=ios&dev=true' --output /dev/null
-            curl --silent 'http://localhost:8081/RNTester/js/RNTesterApp.ios.bundle?platform=ios&dev=true&minify=false' --output /dev/null
-            curl --silent 'http://localhost:8081/IntegrationTests/IntegrationTestsApp.bundle?platform=ios&dev=true' --output /dev/null
-            curl --silent 'http://localhost:8081/IntegrationTests/RCTRootViewIntegrationTestApp.bundle?platform=ios&dev=true' --output /dev/null
-
-      - run:
-          name: Run RNTester Unit Tests
-          command: |
-            source ./scripts/.tests.env
-            xcodebuild \
-              -project RNTester/RNTester.xcodeproj \
-              -scheme RNTester \
-              -sdk iphonesimulator \
-              -destination "platform=iOS Simulator,name=$IOS_DEVICE,OS=$IOS_TARGET_OS" \
-              -UseModernBuildSystem=NO \
-              -only-testing:RNTesterUnitTests \
-              build test | \
-            xcpretty --report junit --output "$REPORTS_DIR/junit/ios_unit_tests/results.xml" && \
-            exit "${PIPESTATUS[0]}"
-
-      - run:
-          name: Run RNTester Integration Tests
-          command: |
-            source ./scripts/.tests.env
-            xcodebuild \
-              -project RNTester/RNTester.xcodeproj \
-              -scheme RNTester \
-              -sdk iphonesimulator \
-              -destination "platform=iOS Simulator,name=$IOS_DEVICE,OS=$IOS_TARGET_OS" \
-              -UseModernBuildSystem=NO \
-              -only-testing:RNTesterIntegrationTests \
-              build test | \
-            xcpretty --report junit --output "$REPORTS_DIR/junit/ios_integration_tests/results.xml" && \
-            exit "${PIPESTATUS[0]}"
-
-      - run:
-          name: Stop Metro packager and WebSocket test server
-          command: |
-            # kill whatever is occupying port 8081 (packager)
-            lsof -i tcp:8081 | awk 'NR!=1 {print $2}' | xargs kill
-            # kill whatever is occupying port 5555 (web socket server)
-            lsof -i tcp:5555 | awk 'NR!=1 {print $2}' | xargs kill
+          name: iOS Test Suite
+          command: ./scripts/objc-test-ios.sh test
 
       - run:
           name: iOS End-to-End Test Suite
diff --git a/RNTester/RNTesterUnitTests/RCTBundleURLProviderTests.m b/RNTester/RNTesterUnitTests/RCTBundleURLProviderTests.m
index 9874b86b9c8d6c..b1f7c204c7be53 100644
--- a/RNTester/RNTesterUnitTests/RCTBundleURLProviderTests.m
+++ b/RNTester/RNTesterUnitTests/RCTBundleURLProviderTests.m
@@ -64,9 +64,6 @@ - (void)tearDown
   [super tearDown];
 }
 
-/**
- * TODO: t43430850: Temporarily disable testBundleURL test.
- * To be re-enabled when the packager can be reliably used on Sandcastle.
 - (void)testBundleURL
 {
   RCTBundleURLProvider *settings = [RCTBundleURLProvider sharedSettings];
@@ -78,7 +75,6 @@ - (void)testBundleURL
     XCTAssertEqualObjects(URL, localhostBundleURL());
   }
 }
- */
 
 - (void)testLocalhostURL
 {
diff --git a/scripts/.tests.env b/scripts/.tests.env
index a34b26404f31ad..d8c1d907761a92 100644
--- a/scripts/.tests.env
+++ b/scripts/.tests.env
@@ -17,7 +17,7 @@ export AVD_NAME="testAVD"
 export AVD_ABI=x86
 
 ## IOS ##
-export IOS_TARGET_OS="12.2"
+export IOS_TARGET_OS="12.1"
 export IOS_DEVICE="iPhone 6s"
 export TVOS_DEVICE="Apple TV"