If you are writing normal UIViewController code, you don't need to worry about thread-safety in iOS. In iOS, any message about UI should be running on the main thread.

If you don't perform some message in background by you self, normally, you don't have to worry about thread, in most situations, it will always be on the main thread.

P.S. Some Frameworks like Game Kit will some times perform messages in background, but it's not about UI and the document from Apple will warn you to make sure if the message is running on main thread.

When do I need to worry about thread-safety in an iOS application?
I have feature class with 70,000+ records (file geodatabase). 
I want to make in bulk update on an attribute where the value is NULL.
Select by attribute shows that I have 5,000 records like that. Doing it one by one is going to be a pain.

In sql pseudo code it should be something like that:

 UPDATE &lt;MyAttributeName&gt; = 'NewValue'
 WHERE &lt;MyAttributeName&gt; IS NULL


How do I do that with ArcMap 10.1?
