Crashes when pushing to viewcontroller - Objective c

Crashes when pushing to viewcontroller - Objective c

My app getting crashed when I try to push to a view controller. Its
happening only when we try to navigate to another page(both push and
presentModal). And I also checked the IBoutlets and other connections in
view controller where it should be pushed. But can't find a clue. Here is
my code where I do the push:
PhoneBookView *phoneBook = [[PhoneBookView alloc]
initWithNibName:@"PhoneBook" bundle:[NSBundle mainBundle]];
[self.navigationController presentModalViewController:phoneBook
animated:YES];
Thanks.