UIAddressBook code puts error on device - iphone

Question

I testing following code on simulator ,it works fine but when I select the device and run then it gives exception .
ABAddressBookRef addressBook = ABAddressBookCreate();
CFArrayRef allPeople = ABAddressBookCopyArrayOfAllPeople(addressBook);
CFIndex nPeople = ABAddressBookGetPersonCount(addressBook);
tempPeoples= [NSMutableArray arrayWithCapacity:0];
for(int i=0;i<nPeople;i++){
ABRecordRef i1=CFArrayGetValueAtIndex(allPeople, i);
NSString* name = (NSString *)ABRecordCopyValue(i1,kABPersonFirstNameProperty);
[tempPeoples addObject:name];
// [peoples addObject:i1];
}// end of
following exception occurs
2011-01-06 12:12:42.384 Appointment[2849:207] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[NSCFArray insertObject:atIndex:]: attempt to insert nil'
2011-01-06 12:12:42.397 Appointment[2849:207] Stack: (
843263261,
825818644,
842812211,
842812115
Please help

Answer 1

You're adding a nil to an array (as the message says)
By a process of deduction, I see that you are adding objects to an array at this line
[tempPeoples addObject:name];
So it is likely that, for this snippet of code, this is where the error happens.
Probably, Not all of the Contacts have a first name, which is likely to be the case for contacts that are businesses rather than people.
You could put a breakpoint in the code and run it through a debugger to see what conditions cause this.