If you cannot see the Ogre templates when you go to Xcode > File > New Project... these steps should fix the issue. I will not explain how to install the SDK, the dependencies, or the templates. I also will not describe how to fix path issues which occur when you first try to run the Ogre templates. A quick google search should show many results for both of those subjects.
First off, make sure that you Installed the OgreSDK, the Ogre Dependencies, and the Ogre Templates for Xcode. Go to Xcode, and click File > New Project... If you see this screen (notice there are no "Ogre" template options on the left) then your templates are not being displayed correctly.
Close Xcode and navigate a finder window to /Library/Application Support/Developer. You should see a window like this.
Right click on Shared and click Get Info. You will then come to this screen.
Notice how it says "You have no access". We will need to fix this before you can see the Ogre templates. Click on the lock at the bottom right corner and enter the required administrator password. Then click on the Privilege that says "No Access". and change the value to "Read & Write". It should now look like this.
Now click the lock to prevent further changes, and close the "Get Info" window. The Shared folder should no longer have a little red circle at the bottom right (like in screenshot 2).
If you open up the Shared folder you should find the folders for the Ogre templates.
If you do not see these folders, then you may need to reinstall the Ogre Templates. Now when you go to create a new Xcode project, Your Ogre templates will be displayed correctly.