问题
During the execution of my program I'm getting the following output in the XCode debugging console:
<Error>: CGContextSetTextMatrix: invalid context 0x0
I have no idea where in the application this NULL-context is being passed to the OS. Anyone know of a good technique to hunt it down? Can I break into the application when something is written to stdout?
回答1:
Adding a breakpoint in the gdb console for CGPostError breaks when the OS writes a CG-related error to stderr.
来源：https://stackoverflow.com/questions/1876017/debugging-a-null-cgcontext-under-cocoa-carbon