iphone - update UI always on Main Thread?

Question

I know Apple said all UI-related operations should be carried out on main thread.

So my question is "all UI-related operations" really mean every possible UI-related operaton?

For example, I will addSubview ViewB to ViewA in a separate thread. Should I always use [ViewA performSelectorOnMaintThread:@selector(addSubview:)...... on the separate thread?

thanks

Answer 1

Yes.

It will crash otherwise.

Answer 2

Yes, You should deal with all about UI in the main-thread. If you are under MFC, you should be in the same manner.

Answer 3

Grand Central Dispatch does things in background threads (for example this line: dispatch_async(dispatch_get_main_queue(), myBlock);) and no crash at all. And i do a lot of things on myBlock()