Setup:
Xcode 4.3.1 (or 5.x)
OS X 10.7.3
I have reproduced this issue on two separate late-model Macs with this setup.
Steps:
- Create a new Mac “Cocoa Application” Xcode Project.
File > New > Project…Name it “MyApp”. - Create a new Workspace:
File > New > Workspace…Name it “MySuite”. - Drag
MyApp.xcodeprojfile from the Finder into the Project Navigator of “MySuite” Workspace.
Expected:
The Project Navigator of the “MySuite” Workspace should now show a full sub-Project for “MyApp” with Source, Targets, etc.
Actual:
“MySuite” Workspace Project Navigator shows a tiny MyApp.xcodeproj item in the Project Navigator. (see screenshots)
Dragging:

Result:

What am I doing wrong in trying to add a Project to a Workspace?
Be sure you don’t have the project already open in another window. Xcode only lets you open a project one time. I’ve made this mistake a lot when working on a framework then trying to add it to an application.
Simply close the project you’re trying to drag in’s window and everything will be happy.