From dd1d1630b4149a19a0d8990352baff798c8d2fc8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20Bj=C3=B6rk?= <phb@spotify.com>
Date: Sun, 30 Jan 2011 22:45:00 +0100
Subject: [PATCH] Xcode: Remember generated ObjectIDs in the cache to allow functional <user>.pbxuser files to work.

---
 Source/cmGlobalXCodeGenerator.cxx |   23 ++++++++++++++++++++++-
 Source/cmGlobalXCodeGenerator.h   |    2 ++
 Source/cmXCodeObject.cxx          |    3 +++
 Source/cmXCodeObject.h            |    5 +++++
 4 files changed, 32 insertions(+), 1 deletions(-)

diff --git a/Source/cmGlobalXCodeGenerator.cxx b/Source/cmGlobalXCodeGenerator.cxx
index 358721f..0096e81 100644
--- a/Source/cmGlobalXCodeGenerator.cxx
+++ b/Source/cmGlobalXCodeGenerator.cxx
@@ -1984,7 +1984,7 @@ cmGlobalXCodeGenerator::CreateUtilityTarget(cmTarget& cmtarget)
         }
       }
     }
-
+  target->SetId(this->GetOrCreateId(cmtarget.GetName(),target->GetId()).c_str());
   return target;
 }
 
@@ -2126,6 +2126,7 @@ cmGlobalXCodeGenerator::CreateXCodeTarget(cmTarget& cmtarget,
     target->AddAttribute("productType", this->CreateString(productType));
     }
   target->SetTarget(&cmtarget);
+  target->SetId(this->GetOrCreateId(cmtarget.GetName(),target->GetId()).c_str());
   return target;
 }
 
@@ -2148,6 +2149,22 @@ cmXCodeObject* cmGlobalXCodeGenerator::FindXCodeTarget(cmTarget* t)
   return 0;
 }
 
+std::string cmGlobalXCodeGenerator::GetOrCreateId(const char* name, const char* id)
+{
+  std::string guidStoreName = name;
+  guidStoreName += "_GUID_CMAKE";
+  const char* storedGUID = this->CMakeInstance->GetCacheDefinition(guidStoreName.c_str());
+  if(storedGUID)
+    {
+    return storedGUID;
+    }
+
+  this->CMakeInstance->AddCacheEntry(guidStoreName.c_str(),
+                                     id, "Stored XCode object GUID", 
+                                     cmCacheManager::INTERNAL);
+  return id;
+}
+
 //----------------------------------------------------------------------------
 void cmGlobalXCodeGenerator::AddDependTarget(cmXCodeObject* target,
                                              cmXCodeObject* dependTarget)
@@ -2615,6 +2632,9 @@ void cmGlobalXCodeGenerator
 
   this->RootObject = this->CreateObject(cmXCodeObject::PBXProject);
   this->RootObject->SetComment("Project object");
+
+  this->RootObject->SetId(this->GetOrCreateId(root->GetMakefile()->GetProjectName(),this->RootObject->GetId()).c_str());
+
   group = this->CreateObject(cmXCodeObject::ATTRIBUTE_GROUP);
   this->RootObject->AddAttribute("mainGroup",
                              this->CreateObjectReference(mainGroup));
@@ -3018,6 +3038,7 @@ cmGlobalXCodeGenerator::OutputXCodeProject(cmLocalGenerator* root,
     }
   this->WriteXCodePBXProj(fout, root, generators);
   this->ClearXCodeObjects();
+  root->GetMakefile()->GetCacheManager()->SaveCache(root->GetMakefile()->GetHomeOutputDirectory());
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmGlobalXCodeGenerator.h b/Source/cmGlobalXCodeGenerator.h
index 290532a..00f38ff 100644
--- a/Source/cmGlobalXCodeGenerator.h
+++ b/Source/cmGlobalXCodeGenerator.h
@@ -121,6 +121,8 @@ private:
                                 );
   
   cmXCodeObject* FindXCodeTarget(cmTarget*);
+  std::string GetOrCreateId(const char* name, const char* id);
+
   // create cmXCodeObject from these functions so that memory can be managed
   // correctly.  All objects created are stored in this->XCodeObjects.
   cmXCodeObject* CreateObject(cmXCodeObject::PBXType ptype);
diff --git a/Source/cmXCodeObject.cxx b/Source/cmXCodeObject.cxx
index 5920470..79407f1 100644
--- a/Source/cmXCodeObject.cxx
+++ b/Source/cmXCodeObject.cxx
@@ -33,6 +33,9 @@ cmXCodeObject::~cmXCodeObject()
 }
 
 //----------------------------------------------------------------------------
+//We set the Id of an xcode object to a unique number for every new generation.
+//However the XCode user file references certain Ids, for those cases, we override
+//the generated Id using SetId().
 cmXCodeObject::cmXCodeObject(PBXType ptype, Type type)
 {
   this->Version = 15;
diff --git a/Source/cmXCodeObject.h b/Source/cmXCodeObject.h
index 2bea63b..c0729d1 100644
--- a/Source/cmXCodeObject.h
+++ b/Source/cmXCodeObject.h
@@ -79,10 +79,15 @@ public:
 
   static void PrintList(std::vector<cmXCodeObject*> const&, 
                         std::ostream& out);
+
   const char* GetId()
     {
       return this->Id.c_str();
     }
+  void SetId(const char* id)
+    {
+      this->Id = id;
+    }
   cmTarget* GetTarget()
     {
       return this->Target;
-- 
1.7.2.1

From 41e4f27a969cdfd6e3591d858cdd05fbd9d23e8f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20Bj=C3=B6rk?= <phb@spotify.com>
Date: Mon, 31 Jan 2011 19:43:05 +0100
Subject: [PATCH] xcode: Remember generated objectIDs in the CMakeCache to allow <user>.pbxuser to work after source regeneration.

---
 Source/cmGlobalXCodeGenerator.cxx |   26 +++++++++++++++++++++++++-
 Source/cmGlobalXCodeGenerator.h   |    2 ++
 Source/cmXCodeObject.cxx          |    3 +++
 Source/cmXCodeObject.h            |    5 +++++
 4 files changed, 35 insertions(+), 1 deletions(-)

diff --git a/Source/cmGlobalXCodeGenerator.cxx b/Source/cmGlobalXCodeGenerator.cxx
index 358721f..c25eef6 100644
--- a/Source/cmGlobalXCodeGenerator.cxx
+++ b/Source/cmGlobalXCodeGenerator.cxx
@@ -1984,7 +1984,7 @@ cmGlobalXCodeGenerator::CreateUtilityTarget(cmTarget& cmtarget)
         }
       }
     }
-
+  target->SetId(this->GetOrCreateId(cmtarget.GetName(),target->GetId()).c_str());
   return target;
 }
 
@@ -2126,6 +2126,7 @@ cmGlobalXCodeGenerator::CreateXCodeTarget(cmTarget& cmtarget,
     target->AddAttribute("productType", this->CreateString(productType));
     }
   target->SetTarget(&cmtarget);
+  target->SetId(this->GetOrCreateId(cmtarget.GetName(),target->GetId()).c_str());
   return target;
 }
 
@@ -2148,6 +2149,23 @@ cmXCodeObject* cmGlobalXCodeGenerator::FindXCodeTarget(cmTarget* t)
   return 0;
 }
 
+std::string cmGlobalXCodeGenerator::GetOrCreateId(const char* name, const char* id)
+{
+  std::string guidStoreName = name;
+  guidStoreName += "_GUID_CMAKE";
+  const char* storedGUID = this->CMakeInstance->GetCacheDefinition(guidStoreName.c_str());
+
+  if(storedGUID)
+    {
+    return storedGUID;
+    }
+
+  this->CMakeInstance->AddCacheEntry(guidStoreName.c_str(),
+                                     id, "Stored XCode object GUID", 
+                                     cmCacheManager::INTERNAL);
+  return id;
+}
+
 //----------------------------------------------------------------------------
 void cmGlobalXCodeGenerator::AddDependTarget(cmXCodeObject* target,
                                              cmXCodeObject* dependTarget)
@@ -2615,6 +2633,11 @@ void cmGlobalXCodeGenerator
 
   this->RootObject = this->CreateObject(cmXCodeObject::PBXProject);
   this->RootObject->SetComment("Project object");
+
+  std::string project_id = "PROJECT_";
+  project_id += root->GetMakefile()->GetProjectName();
+  this->RootObject->SetId(this->GetOrCreateId(project_id.c_str(),this->RootObject->GetId()).c_str());
+
   group = this->CreateObject(cmXCodeObject::ATTRIBUTE_GROUP);
   this->RootObject->AddAttribute("mainGroup",
                              this->CreateObjectReference(mainGroup));
@@ -3018,6 +3041,7 @@ cmGlobalXCodeGenerator::OutputXCodeProject(cmLocalGenerator* root,
     }
   this->WriteXCodePBXProj(fout, root, generators);
   this->ClearXCodeObjects();
+  root->GetMakefile()->GetCacheManager()->SaveCache(root->GetMakefile()->GetHomeOutputDirectory());
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmGlobalXCodeGenerator.h b/Source/cmGlobalXCodeGenerator.h
index 290532a..00f38ff 100644
--- a/Source/cmGlobalXCodeGenerator.h
+++ b/Source/cmGlobalXCodeGenerator.h
@@ -121,6 +121,8 @@ private:
                                 );
   
   cmXCodeObject* FindXCodeTarget(cmTarget*);
+  std::string GetOrCreateId(const char* name, const char* id);
+
   // create cmXCodeObject from these functions so that memory can be managed
   // correctly.  All objects created are stored in this->XCodeObjects.
   cmXCodeObject* CreateObject(cmXCodeObject::PBXType ptype);
diff --git a/Source/cmXCodeObject.cxx b/Source/cmXCodeObject.cxx
index 5920470..79407f1 100644
--- a/Source/cmXCodeObject.cxx
+++ b/Source/cmXCodeObject.cxx
@@ -33,6 +33,9 @@ cmXCodeObject::~cmXCodeObject()
 }
 
 //----------------------------------------------------------------------------
+//We set the Id of an xcode object to a unique number for every new generation.
+//However the XCode user file references certain Ids, for those cases, we override
+//the generated Id using SetId().
 cmXCodeObject::cmXCodeObject(PBXType ptype, Type type)
 {
   this->Version = 15;
diff --git a/Source/cmXCodeObject.h b/Source/cmXCodeObject.h
index 2bea63b..c0729d1 100644
--- a/Source/cmXCodeObject.h
+++ b/Source/cmXCodeObject.h
@@ -79,10 +79,15 @@ public:
 
   static void PrintList(std::vector<cmXCodeObject*> const&, 
                         std::ostream& out);
+
   const char* GetId()
     {
       return this->Id.c_str();
     }
+  void SetId(const char* id)
+    {
+      this->Id = id;
+    }
   cmTarget* GetTarget()
     {
       return this->Target;
-- 
1.7.2.1

From b7b16efa92ac5f41bc514442ddd7b9d00518e55f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20Bj=C3=B6rk?= <phb@spotify.com>
Date: Tue, 15 Feb 2011 15:15:39 +0100
Subject: [PATCH 2/2] XCode: Reuse ObjectIDs. This version uses CoreFoundation to get a UUID, then as an extra check we verify that we don't create duplicates, as it creates hard to track down issues with XCode.

---
 Source/cmGlobalXCodeGenerator.cxx |   45 +++++++++++++++++++++++++++++++++---
 Source/cmGlobalXCodeGenerator.h   |    4 +++
 Source/cmXCodeObject.cxx          |   26 +++++++++------------
 Source/cmXCodeObject.h            |    5 ++++
 4 files changed, 61 insertions(+), 19 deletions(-)

diff --git a/Source/cmGlobalXCodeGenerator.cxx b/Source/cmGlobalXCodeGenerator.cxx
index 9b97dbf..ac1d38c 100644
--- a/Source/cmGlobalXCodeGenerator.cxx
+++ b/Source/cmGlobalXCodeGenerator.cxx
@@ -21,7 +21,7 @@
 #include "cmCustomCommandGenerator.h"
 
 #include <cmsys/auto_ptr.hxx>
-
+#include <assert.h>
 //----------------------------------------------------------------------------
 #if defined(CMAKE_BUILD_WITH_CMAKE)
 #include "cmXMLParser.h"
@@ -456,12 +456,25 @@ void cmGlobalXCodeGenerator::ClearXCodeObjects()
     delete this->XCodeObjects[i];
     }
   this->XCodeObjects.clear();
+  this->XCodeObjectIDs.clear();
   this->GroupMap.clear();
   this->GroupNameMap.clear();
   this->TargetGroup.clear();
   this->FileRefs.clear();
 }
 
+/* XCode will freak out if we happen to generate two identical object IDs, so let's verify we don't */
+void cmGlobalXCodeGenerator::addObject(cmXCodeObject *obj)
+{
+  if(obj->GetType() == cmXCodeObject::OBJECT)
+    {
+    cmStdString id = obj->GetId();
+    assert(!this->XCodeObjectIDs.count(id));
+    this->XCodeObjectIDs.insert(id);
+    }
+  this->XCodeObjects.push_back(obj);
+}
+
 //----------------------------------------------------------------------------
 cmXCodeObject*
 cmGlobalXCodeGenerator::CreateObject(cmXCodeObject::PBXType ptype)
@@ -475,7 +488,7 @@ cmGlobalXCodeGenerator::CreateObject(cmXCodeObject::PBXType ptype)
     {
     obj = new cmXCode21Object(ptype, cmXCodeObject::OBJECT);
     }
-  this->XCodeObjects.push_back(obj);
+  addObject(obj);
   return obj;
 }
 
@@ -484,7 +497,7 @@ cmXCodeObject*
 cmGlobalXCodeGenerator::CreateObject(cmXCodeObject::Type type)
 {
   cmXCodeObject* obj = new cmXCodeObject(cmXCodeObject::None, type);
-  this->XCodeObjects.push_back(obj);
+  addObject(obj);
   return obj;
 }
 
@@ -2021,7 +2034,7 @@ cmGlobalXCodeGenerator::CreateUtilityTarget(cmTarget& cmtarget)
         }
       }
     }
-
+  target->SetId(this->GetOrCreateId(cmtarget.GetName(),target->GetId()).c_str());
   return target;
 }
 
@@ -2170,6 +2183,7 @@ cmGlobalXCodeGenerator::CreateXCodeTarget(cmTarget& cmtarget,
     target->AddAttribute("productType", this->CreateString(productType));
     }
   target->SetTarget(&cmtarget);
+  target->SetId(this->GetOrCreateId(cmtarget.GetName(),target->GetId()).c_str());
   return target;
 }
 
@@ -2192,6 +2206,23 @@ cmXCodeObject* cmGlobalXCodeGenerator::FindXCodeTarget(cmTarget* t)
   return 0;
 }
 
+std::string cmGlobalXCodeGenerator::GetOrCreateId(const char* name, const char* id)
+{
+  std::string guidStoreName = name;
+  guidStoreName += "_GUID_CMAKE";
+  const char* storedGUID = this->CMakeInstance->GetCacheDefinition(guidStoreName.c_str());
+
+  if(storedGUID)
+    {
+    return storedGUID;
+    }
+
+  this->CMakeInstance->AddCacheEntry(guidStoreName.c_str(),
+                                     id, "Stored XCode object GUID", 
+                                     cmCacheManager::INTERNAL);
+  return id;
+}
+
 //----------------------------------------------------------------------------
 void cmGlobalXCodeGenerator::AddDependTarget(cmXCodeObject* target,
                                              cmXCodeObject* dependTarget)
@@ -2689,6 +2720,11 @@ void cmGlobalXCodeGenerator
 
   this->RootObject = this->CreateObject(cmXCodeObject::PBXProject);
   this->RootObject->SetComment("Project object");
+
+  std::string project_id = "PROJECT_";
+  project_id += root->GetMakefile()->GetProjectName();
+  this->RootObject->SetId(this->GetOrCreateId(project_id.c_str(),this->RootObject->GetId()).c_str());
+
   group = this->CreateObject(cmXCodeObject::ATTRIBUTE_GROUP);
   this->RootObject->AddAttribute("mainGroup",
                              this->CreateObjectReference(mainGroup));
@@ -3092,6 +3128,7 @@ cmGlobalXCodeGenerator::OutputXCodeProject(cmLocalGenerator* root,
     }
   this->WriteXCodePBXProj(fout, root, generators);
   this->ClearXCodeObjects();
+  root->GetMakefile()->GetCacheManager()->SaveCache(root->GetMakefile()->GetHomeOutputDirectory());
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmGlobalXCodeGenerator.h b/Source/cmGlobalXCodeGenerator.h
index 22a78f2..10aa828 100644
--- a/Source/cmGlobalXCodeGenerator.h
+++ b/Source/cmGlobalXCodeGenerator.h
@@ -123,6 +123,8 @@ private:
                                 );
   
   cmXCodeObject* FindXCodeTarget(cmTarget*);
+  std::string GetOrCreateId(const char* name, const char* id);
+
   // create cmXCodeObject from these functions so that memory can be managed
   // correctly.  All objects created are stored in this->XCodeObjects.
   cmXCodeObject* CreateObject(cmXCodeObject::PBXType ptype);
@@ -197,9 +199,11 @@ protected:
 
   unsigned int XcodeVersion;
   std::string VersionString;
+  std::set<cmStdString> XCodeObjectIDs;
   std::vector<cmXCodeObject*> XCodeObjects;
   cmXCodeObject* RootObject;
 private:
+  void addObject(cmXCodeObject *obj);
   cmXCodeObject* MainGroupChildren;
   cmXCodeObject* SourcesGroupChildren;
   cmXCodeObject* ResourcesGroupChildren;
diff --git a/Source/cmXCodeObject.cxx b/Source/cmXCodeObject.cxx
index 5920470..7a380be 100644
--- a/Source/cmXCodeObject.cxx
+++ b/Source/cmXCodeObject.cxx
@@ -12,6 +12,7 @@
 #include "cmXCodeObject.h"
 #include "cmSystemTools.h"
 
+#include <CoreFoundation/CoreFoundation.h> //For UUID generation
 //----------------------------------------------------------------------------
 const char* cmXCodeObject::PBXTypeNames[] = {
     "PBXGroup", "PBXBuildStyle", "PBXProject", "PBXHeadersBuildPhase", 
@@ -33,6 +34,9 @@ cmXCodeObject::~cmXCodeObject()
 }
 
 //----------------------------------------------------------------------------
+//We set the Id of an xcode object to a unique number for every new generation.
+//However the XCode user file references certain Ids, for those cases, we override
+//the generated Id using SetId().
 cmXCodeObject::cmXCodeObject(PBXType ptype, Type type)
 {
   this->Version = 15;
@@ -43,27 +47,19 @@ cmXCodeObject::cmXCodeObject(PBXType ptype, Type type)
   this->IsA = ptype;
   if(type == OBJECT)
     {
-    cmOStringStream str;
-    str << (void*)this;
-    str << (void*)this;
-    str << (void*)this;
-    this->Id = str.str();
+      char cUuid[40];
+      CFUUIDRef uuid = CFUUIDCreate(kCFAllocatorDefault);
+      CFStringRef s = CFUUIDCreateString(kCFAllocatorDefault,uuid);
+      assert(CFStringGetCString(s,cUuid,sizeof(cUuid),kCFStringEncodingUTF8));
+      this->Id = cUuid;
+      CFRelease(uuid);
     }
   else
     {
     this->Id = 
       "Temporary cmake object, should not be refered to in xcode file";
     }
-  cmSystemTools::ReplaceString(this->Id, "0x", "");
-  this->Id = cmSystemTools::UpperCase(this->Id);
-  if(this->Id.size() < 24)
-    {
-    int diff = 24 - this->Id.size();
-    for(int i =0; i < diff; ++i)
-      {
-      this->Id += "0";
-      }
-    }
+  cmSystemTools::ReplaceString(this->Id, "-", "");
   if(this->Id.size() > 24)
     {
     this->Id = this->Id.substr(0,24);
diff --git a/Source/cmXCodeObject.h b/Source/cmXCodeObject.h
index 2bea63b..c0729d1 100644
--- a/Source/cmXCodeObject.h
+++ b/Source/cmXCodeObject.h
@@ -79,10 +79,15 @@ public:
 
   static void PrintList(std::vector<cmXCodeObject*> const&, 
                         std::ostream& out);
+
   const char* GetId()
     {
       return this->Id.c_str();
     }
+  void SetId(const char* id)
+    {
+      this->Id = id;
+    }
   cmTarget* GetTarget()
     {
       return this->Target;
-- 
1.7.2.1

From 561e4781a225f6d6b0c3a9ccb6a8d13072df603c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20Bj=C3=B6rk?= <phb@spotify.com>
Date: Tue, 15 Feb 2011 19:31:57 +0100
Subject: [PATCH] Save objectIDS.

---
 Source/cmGlobalXCodeGenerator.cxx |   45 +++++++++++++++++++++++++++++++++---
 Source/cmGlobalXCodeGenerator.h   |    4 +++
 Source/cmXCodeObject.cxx          |   27 ++++++++++------------
 Source/cmXCodeObject.h            |    5 ++++
 4 files changed, 62 insertions(+), 19 deletions(-)

diff --git a/Source/cmGlobalXCodeGenerator.cxx b/Source/cmGlobalXCodeGenerator.cxx
index c336e08..c85882f 100644
--- a/Source/cmGlobalXCodeGenerator.cxx
+++ b/Source/cmGlobalXCodeGenerator.cxx
@@ -21,7 +21,7 @@
 #include "cmCustomCommandGenerator.h"
 
 #include <cmsys/auto_ptr.hxx>
-
+#include <assert.h>
 //----------------------------------------------------------------------------
 #if defined(CMAKE_BUILD_WITH_CMAKE)
 #include "cmXMLParser.h"
@@ -456,12 +456,25 @@ void cmGlobalXCodeGenerator::ClearXCodeObjects()
     delete this->XCodeObjects[i];
     }
   this->XCodeObjects.clear();
+  this->XCodeObjectIDs.clear();
   this->GroupMap.clear();
   this->GroupNameMap.clear();
   this->TargetGroup.clear();
   this->FileRefs.clear();
 }
 
+/* XCode will freak out if we happen to generate two identical object IDs, so let's verify we don't */
+void cmGlobalXCodeGenerator::addObject(cmXCodeObject *obj)
+{
+  if(obj->GetType() == cmXCodeObject::OBJECT)
+    {
+    cmStdString id = obj->GetId();
+    assert(!this->XCodeObjectIDs.count(id));
+    this->XCodeObjectIDs.insert(id);
+    }
+  this->XCodeObjects.push_back(obj);
+}
+
 //----------------------------------------------------------------------------
 cmXCodeObject*
 cmGlobalXCodeGenerator::CreateObject(cmXCodeObject::PBXType ptype)
@@ -475,7 +488,7 @@ cmGlobalXCodeGenerator::CreateObject(cmXCodeObject::PBXType ptype)
     {
     obj = new cmXCode21Object(ptype, cmXCodeObject::OBJECT);
     }
-  this->XCodeObjects.push_back(obj);
+  addObject(obj);
   return obj;
 }
 
@@ -484,7 +497,7 @@ cmXCodeObject*
 cmGlobalXCodeGenerator::CreateObject(cmXCodeObject::Type type)
 {
   cmXCodeObject* obj = new cmXCodeObject(cmXCodeObject::None, type);
-  this->XCodeObjects.push_back(obj);
+  addObject(obj);
   return obj;
 }
 
@@ -2021,7 +2034,7 @@ cmGlobalXCodeGenerator::CreateUtilityTarget(cmTarget& cmtarget)
         }
       }
     }
-
+  target->SetId(this->GetOrCreateId(cmtarget.GetName(),target->GetId()).c_str());
   return target;
 }
 
@@ -2170,6 +2183,7 @@ cmGlobalXCodeGenerator::CreateXCodeTarget(cmTarget& cmtarget,
     target->AddAttribute("productType", this->CreateString(productType));
     }
   target->SetTarget(&cmtarget);
+  target->SetId(this->GetOrCreateId(cmtarget.GetName(),target->GetId()).c_str());
   return target;
 }
 
@@ -2192,6 +2206,23 @@ cmXCodeObject* cmGlobalXCodeGenerator::FindXCodeTarget(cmTarget* t)
   return 0;
 }
 
+std::string cmGlobalXCodeGenerator::GetOrCreateId(const char* name, const char* id)
+{
+  std::string guidStoreName = name;
+  guidStoreName += "_GUID_CMAKE";
+  const char* storedGUID = this->CMakeInstance->GetCacheDefinition(guidStoreName.c_str());
+
+  if(storedGUID)
+    {
+    return storedGUID;
+    }
+
+  this->CMakeInstance->AddCacheEntry(guidStoreName.c_str(),
+                                     id, "Stored XCode object GUID", 
+                                     cmCacheManager::INTERNAL);
+  return id;
+}
+
 //----------------------------------------------------------------------------
 void cmGlobalXCodeGenerator::AddDependTarget(cmXCodeObject* target,
                                              cmXCodeObject* dependTarget)
@@ -2683,6 +2714,11 @@ void cmGlobalXCodeGenerator
 
   this->RootObject = this->CreateObject(cmXCodeObject::PBXProject);
   this->RootObject->SetComment("Project object");
+
+  std::string project_id = "PROJECT_";
+  project_id += root->GetMakefile()->GetProjectName();
+  this->RootObject->SetId(this->GetOrCreateId(project_id.c_str(),this->RootObject->GetId()).c_str());
+
   group = this->CreateObject(cmXCodeObject::ATTRIBUTE_GROUP);
   this->RootObject->AddAttribute("mainGroup",
                              this->CreateObjectReference(mainGroup));
@@ -3086,6 +3122,7 @@ cmGlobalXCodeGenerator::OutputXCodeProject(cmLocalGenerator* root,
     }
   this->WriteXCodePBXProj(fout, root, generators);
   this->ClearXCodeObjects();
+  root->GetMakefile()->GetCacheManager()->SaveCache(root->GetMakefile()->GetHomeOutputDirectory());
 }
 
 //----------------------------------------------------------------------------
diff --git a/Source/cmGlobalXCodeGenerator.h b/Source/cmGlobalXCodeGenerator.h
index 22a78f2..10aa828 100644
--- a/Source/cmGlobalXCodeGenerator.h
+++ b/Source/cmGlobalXCodeGenerator.h
@@ -123,6 +123,8 @@ private:
                                 );
   
   cmXCodeObject* FindXCodeTarget(cmTarget*);
+  std::string GetOrCreateId(const char* name, const char* id);
+
   // create cmXCodeObject from these functions so that memory can be managed
   // correctly.  All objects created are stored in this->XCodeObjects.
   cmXCodeObject* CreateObject(cmXCodeObject::PBXType ptype);
@@ -197,9 +199,11 @@ protected:
 
   unsigned int XcodeVersion;
   std::string VersionString;
+  std::set<cmStdString> XCodeObjectIDs;
   std::vector<cmXCodeObject*> XCodeObjects;
   cmXCodeObject* RootObject;
 private:
+  void addObject(cmXCodeObject *obj);
   cmXCodeObject* MainGroupChildren;
   cmXCodeObject* SourcesGroupChildren;
   cmXCodeObject* ResourcesGroupChildren;
diff --git a/Source/cmXCodeObject.cxx b/Source/cmXCodeObject.cxx
index 5920470..6ce3b60 100644
--- a/Source/cmXCodeObject.cxx
+++ b/Source/cmXCodeObject.cxx
@@ -12,6 +12,7 @@
 #include "cmXCodeObject.h"
 #include "cmSystemTools.h"
 
+#include <CoreFoundation/CoreFoundation.h> //For UUID generation
 //----------------------------------------------------------------------------
 const char* cmXCodeObject::PBXTypeNames[] = {
     "PBXGroup", "PBXBuildStyle", "PBXProject", "PBXHeadersBuildPhase", 
@@ -33,6 +34,9 @@ cmXCodeObject::~cmXCodeObject()
 }
 
 //----------------------------------------------------------------------------
+//We set the Id of an xcode object to a unique number for every new generation.
+//However the XCode user file references certain Ids, for those cases, we override
+//the generated Id using SetId().
 cmXCodeObject::cmXCodeObject(PBXType ptype, Type type)
 {
   this->Version = 15;
@@ -43,27 +47,20 @@ cmXCodeObject::cmXCodeObject(PBXType ptype, Type type)
   this->IsA = ptype;
   if(type == OBJECT)
     {
-    cmOStringStream str;
-    str << (void*)this;
-    str << (void*)this;
-    str << (void*)this;
-    this->Id = str.str();
+      char cUuid[40] = {0};
+      CFUUIDRef uuid = CFUUIDCreate(kCFAllocatorDefault);
+      CFStringRef s = CFUUIDCreateString(kCFAllocatorDefault,uuid);
+      CFStringGetCString(s,cUuid,sizeof(cUuid),kCFStringEncodingUTF8);
+      this->Id = cUuid;
+      CFRelease(s);
+      CFRelease(uuid);
     }
   else
     {
     this->Id = 
       "Temporary cmake object, should not be refered to in xcode file";
     }
-  cmSystemTools::ReplaceString(this->Id, "0x", "");
-  this->Id = cmSystemTools::UpperCase(this->Id);
-  if(this->Id.size() < 24)
-    {
-    int diff = 24 - this->Id.size();
-    for(int i =0; i < diff; ++i)
-      {
-      this->Id += "0";
-      }
-    }
+  cmSystemTools::ReplaceString(this->Id, "-", "");
   if(this->Id.size() > 24)
     {
     this->Id = this->Id.substr(0,24);
diff --git a/Source/cmXCodeObject.h b/Source/cmXCodeObject.h
index 2bea63b..c0729d1 100644
--- a/Source/cmXCodeObject.h
+++ b/Source/cmXCodeObject.h
@@ -79,10 +79,15 @@ public:
 
   static void PrintList(std::vector<cmXCodeObject*> const&, 
                         std::ostream& out);
+
   const char* GetId()
     {
       return this->Id.c_str();
     }
+  void SetId(const char* id)
+    {
+      this->Id = id;
+    }
   cmTarget* GetTarget()
     {
       return this->Target;
-- 
1.7.2.1