// Create a scheuler - used to run actions

private let scheduler = ActionScheduler()

// The view we will be animating

private let squareView: UIView = {

let view = UIView(frame: .zero)

view.backgroundColor = UIColor.red

view.center = CGPoint(x: 100, y: 100)

view.frame.size = CGSize(width: 70, height: 70)

return view

}()

// Start the animation on view did load

override func viewDidLoad() {

super.viewDidLoad()

view.addSubview(squareView)

startAnimation()

}

private func startAnimation() {

// Work out the new frame that we want the view to have

let newWidth = CGFloat(200)

let newHeight = CGFloat(100)

let newFrame = CGRect(x: self.view.center.x - newWidth/2,

y: self.view.center.y - newHeight/2,

width: newWidth,

height: newHeight)

// Create an interpolation action

// We can use a closure for the from argument to get the current frame of the view

// Note the use of [unowned self] closures to break retain cycle, as scheduler has the same lifetime as self

let action = InterpolationAction(from: { [unowned self] in self.squareView.frame },

to: newFrame,

duration: 2,

easing: .exponentialInOut,

update: { [unowned self] in self.squareView.frame = $0 })

// Yoyo (run the action back and forth), and repeat it forever

// You can construct YoyoAction and RepeatForeverAction objects manually, but it's easier to use the convenience functions

let repeatedAction = action.yoyo().repeatedForever()

// Run the action

scheduler.run(action: repeatedAction)

}