Loader Animation With CAShapeLayer and CABasicAnimation

LoaderUIView.swift

//
//  LoaderUIView.swift
//
//  Created by Wilson Munoz on 10/23/18.
//  @yosoywil
//	Based on documentation from:
//	https://www.youtube.com/watch?v=O3ltwjDJaMk
//	https://www.raywenderlich.com/449-how-to-implement-a-circular-image-loader-animation-with-cashapelayer

import UIKit

class LoaderUIView: UIView {
	
	
	let circlePathLayer = CAShapeLayer()
	let circleRadius: CGFloat = 20.0
	
	override init(frame: CGRect) {
		super.init(frame: frame)
		configure()
	}
	
	required init?(coder aDecoder: NSCoder) {
		super.init(coder: aDecoder)
		configure()
	}
	
	
	func circleFrame() -> CGRect {
		var circleFrame = CGRect(x: 0, y: 0, width: 2 * circleRadius, height: 2 * circleRadius)
		let circlePathBounds = circlePathLayer.bounds
		circleFrame.origin.x = circlePathBounds.midX - circleFrame.midX
		circleFrame.origin.y = circlePathBounds.midY - circleFrame.midY
		return circleFrame
	}
	
	func circlePath() -> UIBezierPath {
		return UIBezierPath(ovalIn: circleFrame())
	}

	func configure(){
		let center = CGPoint(x: self.bounds.midX, y: self.bounds.midY)
		let circulalPath = UIBezierPath(arcCenter: center, radius: circleRadius,
										startAngle: -.pi / 2,
										endAngle: 2 * .pi, clockwise: true)
		circlePathLayer.path 		         = circulalPath.cgPath //You can also use circlePath().cgPath, but i couldn't find a way to change the startAngle without a new init.
		circlePathLayer.frame				 = bounds
		circlePathLayer.strokeColor          = UIColor.midnightBlue()?.cgColor
		circlePathLayer.lineWidth            = 3
		circlePathLayer.fillColor            = UIColor.clear.cgColor
		circlePathLayer.strokeEnd            = 0
		circlePathLayer.lineCap              = kCALineCapRound
		let basicAnimation                   = CABasicAnimation(keyPath: "strokeEnd")
		basicAnimation.toValue               = 1
		basicAnimation.duration              = 1.2
		basicAnimation.fillMode              = kCAFillModeForwards
		basicAnimation.isRemovedOnCompletion = false
		basicAnimation.repeatCount           = .infinity

		circlePathLayer.add(basicAnimation, forKey: "loadingBasicaAnimation")
		self.layer.addSublayer(circlePathLayer)
	}

}