Debugger falsely shows object as nil until object has been used

I set a breakpoint immediately following these lines:

NSInteger index = [self.aCombobox indexOfSelectedItem];
NSString *nameSelected = [self.names objectAtIndex:index]; 

If I then roll the mouse over nameSelected, it shows a value of “nil.” And if I type “po nameSelected” in the debugger console, it says the string “does not appear to point to a valid object.”

So I added an NSLog to print nameSelected, which duly printed the string. And, once debugger is below the NSLog line, if I roll the mouse over 开发者_C百科nameSelected, it shows the correct value.

Is there some reason why the debugger behaves this way? It makes it harder to identify where the real problem is.

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Me (and millions of other iOS developers) do this all the time and have no issues. Though it seems a stupid query, have you made modifications to the source while debugging (specifically, added lines of code)? If so, the debugger is still pointing to line X from the .o file while your source is out of sync.

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The real answer is Tommy's comment to this old question of mine. It was a Xcode newby mistake. Sorry to have left this hang out there so long,

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Actually, our experience is that the iOS enabled GDB is buggy as anything. We've observed these kinds of bugs quite often. There might be a solution, but most of the time we just sucked it up and resorted to NSLog Debugging.