I need to run a complex custom animation in an iOS app. For this, I wrote a function that needs to be called repeatedly and uses the current time-stamp to calculate positions, colors, shadows, etc. of UIView elements on the screen.

There seem to be a whole bunch of different approaches I could use to have this function called:

* [Multi-Threading](https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/Multithreading/CreatingThreads/CreatingThreads.html)
* [Timers](https://developer.apple.com/Library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSTimer_Class/index.html)
* [Dispatch Queues](https://developer.apple.com/library/ios/documentation/General/Conceptual/ConcurrencyProgrammingGuide/OperationQueues/OperationQueues.html)
* God knows what else... :)

I tried calling my animation-function from a separate thread first, but while the thread does run, I don't see any screen updates until I trigger a refresh manually with a device rotation, so I must be missing some step where I call the update functions from inside the GUI Thread instead of my own or invalidating the View or something... But I don't even know if this is the best approach...

What is the preferred way to keep calling a function (for an animation, for example) as quickly as possible (or with a small delay of 10ms or so) without blocking the GUI and in such a way that if this function, for example, changes the background color or position of a view, the screen gets updated?

If possible, I would like to use a method that is as backward-compatible as possible, so preferably something that doesn't use any features introduced in iOS 8.1 (exaggeration)... :)

*Aside:*

*Sorry for not posting a code example. I'm using RoboVM and don't want to "scare off" any answers from true XCode developers. Also, this is more of a general conceptual question rather than a specific bug-fix.*