UIAlertView adding NSString

I want to add string to message of my UIAlertView

-(void) errorState:(NSException *) exp
{
    NSLog(@"Error State Blood Level3 %@",exp);
    NSString * myString = (NSString*)exp;
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:myString delegate:self cancelButtonTitle:@"Go to the main menu" otherButtonTitles:nil];
    [alert show];
    [alert release];


}

2010-07-15 12:48:34.721 kndFrameV02[7955:207] -[NSException isEqualToString:]: unrecognized selector sent to instance 0x707b2e0
2010-07-15 12:48:34.724 kndFrameV02[7955:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSException isEqualToString:]: unrecognized selector sent to instance 0x707b2e0'

so how can i add string variable to the message of UIAlertView?

An NSException won't suddenly turn into an NSString when you cast it as one. NSException has a property called reason, that's the one you need. Use it like this: NSString *reason = exp.reason;