[Generator::Xcconfig] Add COCOAPODS macro definition

Closes #903

CHANGELOG.md

+## Master
+
+###### Enhancements
+
+* CocoaPods now defines the `COCOAPODS=1` macro in the Pod and the Client
+  targets. This is useful for libraries which conditionally expose interfaces.
+  [#903](https://github.com/CocoaPods/CocoaPods/issues/903)
+
 ## 0.18.0
 [CocoaPods](https://github.com/CocoaPods/CocoaPods/compare/0.17.2...0.18.0)
 • [cocoapods-core](https://github.com/CocoaPods/Core/compare/0.17.2...0.18.0)

lib/cocoapods/generator/xcconfig.rb

@@ -58,6 +58,7 @@ module Pod
           'PODS_HEADERS_SEARCH_PATHS'        => '${PODS_PUBLIC_HEADERS_SEARCH_PATHS}',
           'PODS_BUILD_HEADERS_SEARCH_PATHS'  => quote(sandbox.build_headers.search_paths),
           'PODS_PUBLIC_HEADERS_SEARCH_PATHS' => quote(sandbox.public_headers.search_paths),
+          'GCC_PREPROCESSOR_DEFINITIONS'     => 'COCOAPODS=1'
         })
 
         spec_consumers.each do |consumer|

spec/integration/install_add_pod/after/Pods/Pods.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/JSONKit" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_custom_workspace/after/Pods/Pods-SampleApp_1.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_custom_workspace/after/Pods/Pods-SampleApp_2.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_external_source/after/Pods/Pods.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/PodTest"

spec/integration/install_local_source/after/Pods/Pods.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_multiple_targets/after/Pods/Pods-SampleApp_2.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/JSONKit" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_multiple_targets/after/Pods/Pods-test.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/JSONKit" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_multiple_targets/after/Pods/Pods.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/JSONKit" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_new/after/Pods/Pods.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_podfile_callbacks/after/Pods/Pods.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_podspec/after/Pods/Pods.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_remove_pod/after/Pods/Pods.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_spec_callbacks/after/Pods/Pods.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/integration/install_subspecs/after/Pods/Pods-OS X App.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/PodTest"

spec/integration/install_subspecs/after/Pods/Pods-iOS App.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/PodTest"

spec/integration/update/after/Pods/Pods.xcconfig

 ALWAYS_SEARCH_USER_PATHS = YES
+GCC_PREPROCESSOR_DEFINITIONS = COCOAPODS=1
 HEADER_SEARCH_PATHS = ${PODS_HEADERS_SEARCH_PATHS}
 OTHER_LDFLAGS = -ObjC -framework SystemConfiguration
 PODS_BUILD_HEADERS_SEARCH_PATHS = "${PODS_ROOT}/BuildHeaders" "${PODS_ROOT}/BuildHeaders/Reachability"

spec/unit/generator/xcconfig_spec.rb

@@ -75,6 +75,10 @@ module Pod
       @xcconfig.to_hash['PODS_PUBLIC_HEADERS_SEARCH_PATHS'].should == expected
     end
 
+    it 'adds the COCOAPODS macro definition' do
+      @xcconfig.to_hash['GCC_PREPROCESSOR_DEFINITIONS'].should == 'COCOAPODS=1'
+    end
+
     it "includes the xcconfig of the specifications" do
       @xcconfig.to_hash['OTHER_LDFLAGS'].should.include('-no_compact_unwind')
     end