Take the 2-minute tour ×  I have a project which worked great
under Xcode 3.2.x. Under Xcode 4.2, I'm getting the following
error when compiling:  "error: unknown type name 'BOOL'; did you
mean 'BOOL'?"  I can right click on the offending BOOL and Xcode
will jump to Apple's definition. BOOL is defined in
<objc/objc.h>, so I included it in my source file (despite the
fact that I'm using precompiled headers with UIKit.h and
Foundation.h). Still no joy - the compile error persists.  Any
ideas for Xcode 4 work arounds would be appreciated. Google is
offering 0 hits.  EDIT: added the offending code to remove any
ambiguity.  // AppConstants.h typedef enum { ThreadPriorityLow =
NSOperationQueuePriorityLow, ThreadPriorityNormal =
NSOperationQueuePriorityNormal,     ThreadPriorityHigh =
NSOperationQueuePriorityHigh, ThreadPriorityDefault =
ThreadPriorityNormal } ThreadPriority;  static inline BOOL
IsValidThreadPriority(ThreadPriority priority)     return
priority == ThreadPriorityLow || priority == ThreadPriorityNorma