How can I create a sequence of functions and loop them in Swift?

Question

I am trying to build a feature so that when you shake the iPhone, the particles on the screen will fly around.

I have hooks to tie into when the shaking begins and ends.

I will create a UIPushBehavior and add it to the animator scene when shaking begins and when it ends I will remove the UIPushBehavior from the animator.

But to get a good shaking experience I want to vary the push angle while the device is in motion.

How can I recreate this pseudo code in Swift?

override func motionBegan(motion: UIEventSubtype, withEvent event: UIEvent!)
{
    if (motion == UIEventSubtype.MotionShake)
    {
        self.push = UIPushBehavior()
        self.push!.angle = -self.angle!
        self.animator.addBehavior(self.push)
        // BEGIN Pseudo Code
        self.sequence = Sequence({self.push.angle = self.angle!}, {self.push.angle = -self.angle}, 
        delay: 100ms)
       // END Pseudo Code
    }
}

override func motionEnded(motion: UIEventSubtype, withEvent event: UIEvent!)
{
    if (motion == UIEventSubtype.MotionShake)
    {

       self.animator.removeBehavior(self.push)
       // BEGIN Pseudo Code
       self.sequence.stopSequence()
       // END Pseudo Code
    }
}

So as you can see I want to be able to define 2 functions (which change the direction of push angle by 180 degrees) to be looped every 100ms, until I call stopSequence()

How can I actually do this with Swift?

Answer 1

Are you looking for something like this:

class MySequence {
  var functions : Array<() -> ()>

  func runSequenceOneTime () -> Void {
    for function in functions {
      function ()
    }
  }

  func stopSequence () -> Void {
    // uninstall alarm
  }

  func startSequence (delay: Double) -> Void {
    // install alarm w/ runSequenceOneTime
  }

  init (delay: Double, _ functions: (() -> ())...) {
    self.functions = functions
    self.startSequence (delay)
  }
}

and then you'd create an instance of MySequence as:

var mySeq = MySequence (delay: 0.1, func1, func2, func3)