Logging and Handling Constants
Use one or more of the following constants in the parameter of Setexceptionhandlingmask(_:) to specify the types of exceptions that the exception handler should monitor and whether it should handle or log them.
Overview
When exception-handling domains are nested, NSLogTopLevelExceptionMask and NSHandleTopLevelExceptionMask deal with exceptions that would make it to the top two levels of exception handlers. In the main thread of a Cocoa application, the top-level handler is the global NSApplication instance.