loop() is used by the Arduino IDE to help people understand, "this will always be running."Programming the Arduino and programming an iOS application have very little in common. Objective-C / CocoaTouch / iOS is fully object oriented system. While Arduino is more of a procedural system.You won't find an equivalent of a loop() in Obj-C because it doesn't really exist. Cocoa applications run in a constant "waiting" state, waiting for events to occur. This is different from Arduino (or microprocessors in general) because you tend to specify what to be doing at any given time. Setting up a while(1) loop in an Objective-C application, to simulate Arduino's loop() would result in a very broken program.