Travis CI: build with Xcode 9.4 image, update the code coverage flag

Author: vbabenkoru

.travis.yml

@@ -1,4 +1,4 @@
-osx_image: xcode9.3
+osx_image: xcode9.4
 language: objective-c
 xcode_workspace: Iterable-iOS-SDK.xcworkspace
 xcode_scheme: Iterable-iOS-SDKTests
@@ -8,9 +8,9 @@ before_install:
   - gem install xcpretty xcpretty-travis-formatter
 
 script:
-  - xcodebuild test -sdk iphonesimulator -destination 'platform=iOS Simulator,name=iPhone X' -workspace Iterable-iOS-SDK.xcworkspace -scheme IterableAppExtensionsTests CODE_SIGNING_REQUIRED=NO GCC_INSTRUMENT_PROGRAM_FLOW_ARCS=YES GCC_GENERATE_TEST_COVERAGE_FILES=YES | xcpretty -f `xcpretty-travis-formatter`
-  - xcodebuild test -sdk iphonesimulator -destination 'platform=iOS Simulator,name=iPhone X' -workspace Iterable-iOS-SDK.xcworkspace -scheme Iterable-iOS-SDKTests CODE_SIGNING_REQUIRED=NO GCC_INSTRUMENT_PROGRAM_FLOW_ARCS=YES GCC_GENERATE_TEST_COVERAGE_FILES=YES | xcpretty -f `xcpretty-travis-formatter`
-  - xcodebuild test -sdk iphonesimulator -destination 'platform=iOS Simulator,name=iPhone 6s,OS=9.0' -workspace Iterable-iOS-SDK.xcworkspace -scheme Iterable-iOS-SDKTests CODE_SIGNING_REQUIRED=NO GCC_INSTRUMENT_PROGRAM_FLOW_ARCS=YES GCC_GENERATE_TEST_COVERAGE_FILES=YES | xcpretty -f `xcpretty-travis-formatter`
+  - xcodebuild test -sdk iphonesimulator -destination 'platform=iOS Simulator,name=iPhone X' -enableCodeCoverage YES -workspace Iterable-iOS-SDK.xcworkspace -scheme IterableAppExtensionsTests CODE_SIGNING_REQUIRED=NO GCC_INSTRUMENT_PROGRAM_FLOW_ARCS=YES GCC_GENERATE_TEST_COVERAGE_FILES=YES | xcpretty -f `xcpretty-travis-formatter`
+  - xcodebuild test -sdk iphonesimulator -destination 'platform=iOS Simulator,name=iPhone X' -enableCodeCoverage YES -workspace Iterable-iOS-SDK.xcworkspace -scheme Iterable-iOS-SDKTests CODE_SIGNING_REQUIRED=NO GCC_INSTRUMENT_PROGRAM_FLOW_ARCS=YES GCC_GENERATE_TEST_COVERAGE_FILES=YES | xcpretty -f `xcpretty-travis-formatter`
+  - xcodebuild test -sdk iphonesimulator -destination 'platform=iOS Simulator,name=iPhone 6s,OS=9.0' -enableCodeCoverage YES -workspace Iterable-iOS-SDK.xcworkspace -scheme Iterable-iOS-SDKTests CODE_SIGNING_REQUIRED=NO GCC_INSTRUMENT_PROGRAM_FLOW_ARCS=YES GCC_GENERATE_TEST_COVERAGE_FILES=YES | xcpretty -f `xcpretty-travis-formatter`
   - pod lib lint
 
 after_success: