sprite-kit Timed functions in SpriteKit: SKActions vs NSTimers

When should you use SKActions to perform timer functions? Almost always. The reason for this is because Sprite Kit operates on an update interval, and the speed of this interval can be changed throughout the life time of the process using the speed property. Scenes can also be paused as well. Since SKActions work inside the scene, when you alter these properties, there is no need to alter your time functions. If your scene is 0.5 seconds into the process, and you pause the scene, you do not need to stop any timers and retain that 0.5 second difference. It is given to you automatically, so that when you unpause, the remaining time continues.

When should you use NSTimers to perform timer functions? Whenever you have something that needs to be timed outside of the SKScene environment, and also needs to be fired even when the scene is paused, or needs to fire at a constant rate even when the scene speed changes.

This is best used when working with both UIKit controls and SpriteKit controls. Since UIKit has no idea about what goes on with SpriteKit, NSTimers will fire regardless of the state of the SKScene. An example would be we have a UILabel that receives an update every second, and it needs data from inside your SKScene.