NSArray is an immutable class, which means that its contents can't be changed after it has been created. If you want to be able to change the contents of your array after it has been created, you should use an NSMutableArray instead. This subclass of NSArray provides additional methods such as:
insertObject:atIndex:
removeObjectAtIndex:
addObject:
removeLastObject
replaceObjectAtIndex:withObject:
Once you've updated your mutable array, you can reload your table by calling [self.tableView reloadData]
.
EDIT:
If you just want to change the value of one of the elements in your array without actually adding or removing any objects, then your array doesn't need to be mutable, but the object you're changing does. So if you have an array of NSString objects, you can change those to NSMutableString objects. Then you can use setString:
on one of those objects to change its value.