code crashes when adding view

I copied all my iphone viewcontroller files into an a new iPad project. (I changed the sizes of each nib files etc.)

Almost all viewControllers are working except for one viewcontroller say xview.

At the line [self.view add:xview.view] the code crashes with the following log

2011-06-22 14:08:56.435 RelaxInAMinutePad[5073:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL initFileURLWithPath:]: nil string parameter'
2011-06-22 14:08:56.437 RelaxInAMinutePad[5073:207] Stack: (
    47421520,
    48579372,
    47159051,
    47158890,
    1569479,
    1563144,
    19971,
    20321,
    19638,
    23235,
    4095877,
    30247,
    5636593,
    3472622,
    3970110,
    3979456,
    3970037,
    3472622,
    3970110,
    3979456,
    3974253,
    3599848,
    3491395,
    3523032,
    56开发者_运维百科414588,
    46700700,
    46696616,
    56408221,
    56408418,
    3515250,
    8984,
    8838
)
terminate called after throwing an instance of 'NSException'

I am not using any URL or anything from my code.

I am not getting why this is caused. I am sure this is not about coding but some thing to do with resources or IB.

what may be the mistake and how to rectify?

Read the console:

  reason: '*** -[NSURL initFileURLWithPath:]: nil string parameter'

Somewhere you are trying to instantiate an NSURL object, but the string you pass into it is nil.

check your line

 [self.view add xview.view]

it should be

 [self.view addSubview xview.view]

Maybe you not add Nib-file in new project, or any other resource files...