fixed bug of directory cleaning.

prevents multiple times to clean the root directory of symlink headers.

lib/cocoapods/config.rb

@@ -40,6 +40,10 @@ module Pod
       @project_podfile
     end
 
+    def headers_symlink_root
+      @headers_symlink_root ||= "#{project_pods_root}/Headers"
+    end
+
     # Returns the spec at the pat returned from `project_podfile`.
     def rootspec
       unless @rootspec

lib/cocoapods/installer.rb

@@ -72,6 +72,10 @@ module Pod
       puts "Installing dependencies of: #{@podfile.defined_in_file}" if config.verbose?
       install_dependencies!
       root = config.project_pods_root
+      headers_symlink_root = config.headers_symlink_root
+
+      # Clean old header symlinks
+      FileUtils.rm_r(headers_symlink_root, :secure => true) if File.exists?(headers_symlink_root)
 
       puts "Generating support files" unless config.silent?
       target_installers.each do |target_installer|

lib/cocoapods/installer/target_installer.rb

@@ -61,18 +61,11 @@ module Pod
         "#{@definition.lib_name}-prefix.pch"
       end
 
-      def headers_symlink_path_name
-        "#{config.project_pods_root}/Headers"
-      end
-
       # TODO move xcconfig related code into the xcconfig method, like copy_resources_script and generate_bridge_support.
       def install!
         # First add the target to the project
         @target = @project.targets.new_static_library(@definition.lib_name)
 
-        # Clean old header symlinks
-        FileUtils.rm_r(headers_symlink_path_name, :secure => true) if File.exists?(headers_symlink_path_name)
-
         header_search_paths = []
         build_specifications.each do |spec|
           xcconfig.merge!(spec.xcconfig)
@@ -82,7 +75,7 @@ module Pod
           end
           # Symlink header files to Pods/Headers
           spec.copy_header_mappings.each do |header_dir, files|
-            target_dir = "#{headers_symlink_path_name}/#{header_dir}"
+            target_dir = "#{config.headers_symlink_root}/#{header_dir}"
             FileUtils.mkdir_p(target_dir)
             target_dir_real_path = Pathname.new(target_dir).realpath
             files.each do |file|

spec/integration_spec.rb

@@ -337,6 +337,33 @@ else
         end
       end
 
+      it "should prevent duplication cleaning headers symlinks with multiple targets" do
+        Pod::Source.reset!
+        Pod::Spec::Set.reset!
+
+        podfile = Pod::Podfile.new do
+          # first ensure that the correct info is available to the specs when they load
+          config.rootspec = self
+          self.platform platform
+          target(:debug) { dependency 'SSZipArchive' }
+          target(:test, :exclusive => true) { dependency 'JSONKit' }
+          dependency 'ASIHTTPRequest'
+        end
+
+        installer = Pod::Installer.new(podfile)
+        installer.install!
+
+        root = config.project_pods_root
+        (root + 'Pods.xcconfig').should.exist
+        (root + 'Headers').should.exist
+        (root + 'Headers/SSZipArchive').should.exist
+        (root + 'Headers/ASIHTTPRequest').should.exist
+        (root + 'Headers/JSONKit').should.exist
+        Pathname.glob(File.join(root.to_s, 'Headers/ASIHTTPRequest/*.h')).size.should.be > 0
+        Pathname.glob(File.join(root.to_s, 'Headers/SSZipArchive/*.h')).size.should.be > 0
+        Pathname.glob(File.join(root.to_s, 'Headers/JSONKit/*.h')).size.should.be > 0
+      end
+
     end
   end