What is an event loop or run loop?

Question

In iPhone development, I have come across these terms named

event loop, run loop

. Can some one explain explain what they are?

Answer 1

Like many other GUI systems, the code you write for an iPhone application runs into a loop that is provided by the system. When writing a program without a GUI it is customary to have a main() function or similar. On iPhone you don't have that because it's provided by the system, and it will call the event loop. All you provide is callbacks to react to events.

The loop takes care of getting hardware events as touches and such, calling your code and API code to draw the windows, some memory management and all. This is why you never have to poll for these events yourself.