XCode 6 Beta 3 using Swift.
In my App I use CoreData. When I run my App in simulator, XCode pops up the debugger with a breakpoint set somewhere in the CoreData libr
Do you have an All Exception breakpoint set?
Contrary to Apple's best practices CoreData uses exceptions in the normal flow of control.
If you add exception breakpoints you may break in CoreData. The solution is to remove or disable the exception breakpoint.