Added unit tests and modified code according to comments.

lib/cocoapods/generator/xcconfig/xcconfig_helper.rb

@@ -284,7 +284,7 @@ module Pod
         def self.add_language_specific_settings(target, xcconfig)
           if target.uses_swift?
             other_swift_flags = ['$(inherited)', quote(%w(-D COCOAPODS))]
-            other_swift_flags += [quote(%w(-suppress-warnings))] if target.try(:inhibit_warnings?)
+            other_swift_flags << quote(%w(-suppress-warnings)) if target.try(:inhibit_warnings?)
             build_settings = { 'OTHER_SWIFT_FLAGS' => other_swift_flags.join(' ') }
             xcconfig.merge!(build_settings)
           end

spec/unit/generator/xcconfig/xcconfig_helper_spec.rb

@@ -194,6 +194,34 @@ module Pod
         end
 
         #---------------------------------------------------------------------#
+        
+        describe '::add_language_specific_settings' do
+          it 'does not add OTHER_SWIFT_FLAGS to the xcconfig if the target does not use swift' do
+            target = stub(:uses_swift? => false)
+            xcconfig = Xcodeproj::Config.new()
+            @sut.add_language_specific_settings(target, xcconfig)
+            other_swift_flags = xcconfig.to_hash['OTHER_SWIFT_FLAGS']
+            other_swift_flags.should == nil
+          end
+          
+          it 'does not add the -suppress-warnings flag to the xcconfig if the target uses swift, but does not inhibit warnings' do
+            target = stub(:uses_swift? => true, :inhibit_warnings? => false)
+            xcconfig = Xcodeproj::Config.new()
+            @sut.add_language_specific_settings(target, xcconfig)
+            other_swift_flags = xcconfig.to_hash['OTHER_SWIFT_FLAGS']
+            other_swift_flags.should.not.include?('-suppress-warnings')
+          end
+          
+          it 'adds the -suppress-warnings flag to the xcconfig if the target uses swift and inhibits warnings' do
+            target = stub(:uses_swift? => true, :inhibit_warnings? => true)
+            xcconfig = Xcodeproj::Config.new()
+            @sut.add_language_specific_settings(target, xcconfig)
+            other_swift_flags = xcconfig.to_hash['OTHER_SWIFT_FLAGS']
+            other_swift_flags.should.include?('-suppress-warnings')
+          end
+        end
+
+        #---------------------------------------------------------------------#
       end
     end
   end