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What causes "NSScanner: nil string argument"?

I got this message when I save data to core data. 

NSScanner: nil string argument

I didn't use any NSScanner method. Where did it come from?

This is a bug? What should I do with it?

Thanks help, please.

Solution

  • From experience, I can say that -[NSDecimalNumber initWithString:] or +[NSDecimalNumber decimalNumberWithString:] with a nil string is one thing that causes that log message.

    Set a breakpoint on -[NSScanner initWithString:] to start with; if you don't catch it that way, then break on the other ways you might create a scanner, like +scannerWithString: and -[NSConcreteScanner initWithString:]. That's how I flushed my unwanted log statement out.