File downloader (in background) with animated circular loading progress bar for swift

UICCircularProgressBar.swift

//
//  UICCircularProgressBar.swift
//  UICCircularDownloadProgressBar
//
//  Created by Coder ACJHP on 1.04.2019.
//  Copyright © 2019 Onur Işık. All rights reserved.
//

import UIKit

protocol UICCircularProgressBarDelegate {
    func didFinishDownloadAndSave(_ successfully: Bool, filePath: String?)
}

class UICCircularProgressBar: UIView, URLSessionDownloadDelegate {
    
    private let trackLayer = CAShapeLayer()
    private let pulsatingLayer = CAShapeLayer()
    private var animationLayer = CAShapeLayer()
    private let mockUrl = URL(string: "http://techslides.com/demos/sample-videos/small.mp4")
    
    // View options
    public private(set) var savedURL: URL?
    public var fileName: String = "test"
    public var fileExtension: String = "mp4"
    public var removeAfterCompletion: Bool = false
    public var hideAfterDelay: TimeInterval = 0
    public var fontColor = UIColor.black {
        didSet {
            percentageLabel.textColor = fontColor
            completedLabel.textColor = fontColor
        }
    }
    public var lineWidth: CGFloat = 20 {
        didSet {
            trackLayer.lineWidth = lineWidth
            animationLayer.lineWidth = lineWidth
        }
    }
    public var strokeColor = UIColor.red {
        didSet {
            animationLayer.strokeColor = strokeColor.cgColor
            trackLayer.strokeColor = strokeColor.withAlphaComponent(0.6).cgColor
            pulsatingLayer.fillColor = strokeColor.withAlphaComponent(0.2).cgColor
        }
    }
    public var fillColor = UIColor.clear {
        didSet {
            trackLayer.fillColor = fillColor.cgColor
            animationLayer.fillColor = fillColor.cgColor
        }
    }
    public var trackStrokeColor = UIColor.lightGray {
        didSet {
            trackLayer.strokeColor = trackStrokeColor.cgColor
        }
    }
    
    public var delegate: UICCircularProgressBarDelegate?
    private var basicAnimation = CABasicAnimation(keyPath: "strokeEnd")
    
    private lazy var percentageLabel: UILabel = {
        let label = UILabel()
        label.font = UIFont.boldSystemFont(ofSize: self.frame.width * 0.2)
        label.textAlignment = .center
        label.textColor = fontColor
        label.text = "0"
        return label
    }()
    
    private lazy var completedLabel: UILabel = {
        let label = UILabel()
        label.font = UIFont.systemFont(ofSize: self.frame.width * 0.09)
        label.textAlignment = .center
        label.adjustsFontSizeToFitWidth = true
        label.textColor = fontColor
        return label
    }()
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        backgroundColor = .clear
        
        self.adjustSelf()
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    fileprivate func adjustSelf() {
        
        self.setupLayers()
        self.setupLabels()
        self.setupAnimation()
        self.initializeSelf()
    }
    
    fileprivate func setupLayers() {
        
        let cRadius = self.bounds.width / 2
        let cEndAngle = CGFloat.pi * 2
        let cStartAngle: CGFloat = 0.0
        let cRotateAngle = -CGFloat.pi / 2
        let path = UIBezierPath.init(arcCenter: CGPoint.zero, radius: cRadius,
                                     startAngle: cStartAngle, endAngle: cEndAngle, clockwise: true).cgPath
        
        pulsatingLayer.path = path
        pulsatingLayer.lineWidth = lineWidth
        pulsatingLayer.lineCap = .round
        pulsatingLayer.fillColor = strokeColor.withAlphaComponent(0.2).cgColor
        layer.addSublayer(pulsatingLayer)
        pulsatingLayer.position = self.center
        
        trackLayer.path = path
        trackLayer.lineWidth = lineWidth
        trackLayer.lineCap = .round
        trackLayer.strokeEnd = 1.0
        trackLayer.fillColor = fillColor.cgColor
        trackLayer.strokeColor = strokeColor.withAlphaComponent(0.8).cgColor
        layer.addSublayer(trackLayer)
        trackLayer.position = self.center
        
        animationLayer.path = path
        animationLayer.lineWidth = lineWidth
        animationLayer.lineCap = .round
        animationLayer.strokeEnd = 0
        animationLayer.fillColor = fillColor.cgColor
        animationLayer.strokeColor = strokeColor.cgColor
        layer.addSublayer(animationLayer)
        animationLayer.position = self.center
        // We must rotate the layer to start from 12 clock position.
        animationLayer.transform = CATransform3DRotate(CATransform3DIdentity, cRotateAngle, 0, 0, 1)
    }
    
    fileprivate func setupLabels() {
        
        let stackView = UIStackView(arrangedSubviews: [percentageLabel, completedLabel])
        stackView.axis = .vertical
        stackView.alignment = .fill
        stackView.distribution = .fillProportionally
        stackView.translatesAutoresizingMaskIntoConstraints = false
        addSubview(stackView)
        
        NSLayoutConstraint.activate([
            stackView.widthAnchor.constraint(equalTo: widthAnchor, constant: -(self.frame.width * 0.4)),
            stackView.heightAnchor.constraint(equalTo: heightAnchor, constant: -(self.frame.height * 0.4)),
            stackView.centerXAnchor.constraint(equalTo: centerXAnchor),
            stackView.centerYAnchor.constraint(equalTo: centerYAnchor),
            ])
    }
    
    fileprivate func setupAnimation() {
        
        // Setup and start pulsating animation
        setupPulsatingAnimation()
        
        basicAnimation.fromValue = 0
        basicAnimation.repeatCount = 0
        basicAnimation.fillMode = .forwards
        basicAnimation.isRemovedOnCompletion = false
        
        // add animation to animating layer
        animationLayer.add(basicAnimation, forKey: "strokeEndAnimation")
    }
    
    fileprivate func setupPulsatingAnimation() {
        
        let pulsatingAnimation = CABasicAnimation(keyPath: "transform.scale")
        pulsatingAnimation.fromValue = 1.0
        pulsatingAnimation.toValue = 1.2
        pulsatingAnimation.duration = 0.8
        pulsatingAnimation.autoreverses = true
        pulsatingAnimation.repeatCount = .infinity
        pulsatingAnimation.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
        pulsatingAnimation.isRemovedOnCompletion = false
        
        // add animation to animating layer
        pulsatingLayer.add(pulsatingAnimation, forKey: "grow&Shrink")
    }
    
    fileprivate func initializeSelf() {
        
        self.alpha = 0
        UIView.animate(withDuration: 1.0, animations: { self.alpha = 1 })
    }
    
    fileprivate func hide() {
        
        perform(#selector(hideYourSelf), with: nil, afterDelay: hideAfterDelay)
    }
    
    @objc fileprivate func hideYourSelf() {
        UIView.animate(withDuration: 1.0, animations: {
            self.alpha = 0
        }, completion: { (_) in
            self.removeFromSuperview()
        })
    }
    
    public func downloadAndSave(fromUrlString: String?, withName: String, suffix: String) {
        
        fileName = withName
        fileExtension = suffix
        // Reset stroke end value to get rid of starting from the half of path
        animationLayer.strokeEnd = 0
        
        let urlSession = URLSession(configuration: URLSessionConfiguration.default,
                                    delegate: self, delegateQueue: OperationQueue())
        
        var url: URL!
        if fromUrlString != nil { url = URL(string: fromUrlString!) } else { url = mockUrl }
        let downloadTask = urlSession.downloadTask(with: url)
        downloadTask.resume()
    }
    
    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
        
        let percentage = CGFloat(totalBytesWritten) / CGFloat(totalBytesExpectedToWrite)
        
        DispatchQueue.main.async {
            self.percentageLabel.text = "\(Int(percentage * 100))%"
            self.animationLayer.strokeEnd = percentage
        }
        
        
    }
    
    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
        
        DispatchQueue.main.async {
            self.completedLabel.text = "COMPLETED!"
            
            if self.removeAfterCompletion {
                self.hide()
            }
        }
        
        guard let httpResponse = downloadTask.response as? HTTPURLResponse,
            (200...299).contains(httpResponse.statusCode) else {
                
                debugPrint("server error");
                delegate?.didFinishDownloadAndSave(false, filePath: nil)
                return
        }
        
        do {
            let documentsURL = try FileManager.default.url(for: .documentDirectory,
                                                           in: .userDomainMask,
                                                           appropriateFor: nil,
                                                           create: false)
            savedURL = documentsURL.appendingPathComponent("\(self.fileName).\(self.fileExtension)")
            
            // Check if file exists
            if FileManager.default.fileExists(atPath: savedURL!.absoluteString) {
                // Delete file
                try FileManager.default.removeItem(atPath: savedURL!.absoluteString)
            } else {
                
                try FileManager.default.moveItem(at: location, to: savedURL!)
                delegate?.didFinishDownloadAndSave(true, filePath: savedURL!.path)
            }
            
        } catch {
            debugPrint("file error: \(error)")
            delegate?.didFinishDownloadAndSave(false, filePath: nil)
        }
    }
}

To get rid of APPTransportSecurity error just add these two lines into your plist file:

<key>NSAppTransportSecurity</key>
	<dict>
		<key>NSAllowsArbitraryLoads</key>
		<true/>
	</dict>