Threads in Simple iOS Application

Question

When I create empty application (with Single view template for example) and if some crash happens, it shows 5 threads in Debug Navigator like Thread-1, Thread-2, Thread-3, Thread-4, Thread-5. I understand Thread-1 which is main application thread, but what are these other threads?

Answer 1

Those are internal threads which are required for every application. By default every app has some threads. In addition to those, you can create additional threads though through

NSTimers, performSelectors, dispatch_async, NSOperations etc