Find line matching error in Xcode debugger

Look in the lines below this,
you should have a backtrace of the methods that you and the system are executing.
There you should find the name of the method in which it occurred.

I just took an existing project and added a similar crash and goal to illustrate this.

My method is -

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];  
    self.contacts = [NSMutableArray arrayWithArray: [ARContact loadContacts]];  
    NSLog(@"%@", self.contacts[100]); // Index 100 is outside of the array scope  
    ....  
}  

      

        
        
        
      

    

Crash console log (at the bottom of Xcode)

*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 100 beyond bounds for empty array'
*** First throw call stack:
(
    0   CoreFoundation                      0x0000000101a87495 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x00000001007ec99e objc_exception_throw + 43
    2   CoreFoundation                      0x0000000101a2d745 -[__NSArrayM objectAtIndex:] + 213
    3   PhoneBookApp                        0x0000000100001f95 -[ViewController viewWillAppear:] + 261
    4   UIKit                               0x0000000100b1adb5 -[UIViewController _setViewAppearState:isAnimating:] + 422
    5   UIKit                               0x0000000100b38c4d -[UINavigationController _startTransition:fromViewController:toViewController:] + 707  

      

        
        
        
      

    

Here you can see things reversed as they occur (meaning 0 is the last thing to run, 1 before that, etc.).

If you look at the numbers 3 and 4, you can see that a method call appears before the failure NSArray

objectAtIndex:

(line 3),
and this method is called from viewWillAppear:

(line 4).