Can you please tell me about this warning?

Question

I'm getting this exception in

[self.navigationcontroller PopViewControllerAnimated:YES];

2010-06-21 19:12:46.585 IChitMe[31250:207] *** -[NSKeyValueIvarSetter addSubview:]: unrecognized selector sent to instance 0x377010
2010-06-21 19:12:46.593 IChitMe[31250:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSKeyValueIvarSetter addSubview:]: unrecognized selector sent to instance 0x377010'
2010-06-21 19:12:46.604 IChitMe[31250:207] Stack: (
    864992541,
    859229716,
    864996349,
    864492313,
    864454720,
    805091,
    795933,
    839415824,
    839414704,
    839684408,
    839683992,
    1282379,
    864749711,
    839231364,
    839683900,
    864749711,
    839231364,
    839231212,
    839231156,
    839230220,
    839233420,
    839227648,
    839225236,
    839206800,
    839205012,
    875886564,
    864740651,
    864738335,
    875880904,
    838872112,
    838865456,
    10345,
    10208
)
terminate called after throwing an instance of 'NSException'
Program received signal:  “SIGABRT”.
(gdb) 

Answer 1

popViewControllerAnimated should start with lowercase p

Answer 2

That looks to me like a UIViewController or UIView has been over-released. You, or iOS, is trying to add a subview to a view, but the message is being sent to a NSKeyValueIvarSetter. In all likelihood, that's because the memory for the intended UIView has been reclaimed and reallocated.