這里是使用方法，可以使用自動布局，會更新進(jìn)度條視圖大小的，最近優(yōu)化了一下命名和背景色也可以漸變的邏輯

class GradientProgressController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.addSubview(self.progressView)
        self.progressView.snp.makeConstraints { make in
            make.top.equalTo(100)
            make.width.height.equalTo(200)
        }

        self.progressView.setProgress(0.5, animated: true, duration: 1.0)
    }
    
    //MARK: - lazy load -
    private lazy var progressView: GradientCircleProgressView = {
        let view = GradientCircleProgressView(frame: CGRect(x: 0, y: 0, width: 100, height: 100), lineWidth: 10, bgColors: [UIColor(hex: "EDEDED").cgColor, UIColor.red.cgColor], bgLocations: [0.0, 1.0], progressColors: [Colors.mainColor.cgColor, Colors.mainColor.cgColor], progressLocations: [0.0, 1.0])
        return view
    }()
}

這個是進(jìn)度條類

class GradientCircleProgressView: UIView {
    
    private var bgColors: [CGColor] = []
    private var lineWidth: CGFloat = 0.0
    private var progressColors: [CGColor] = []
    private var bgLocations: [Double] = []
    private var progressLocations: [Double] = []
    private var progress: CGFloat = 0.0
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
    }
    
    convenience init(frame: CGRect, lineWidth: CGFloat, bgColors: [CGColor], bgLocations: [Double], progressColors: [CGColor], progressLocations: [Double]) {
        self.init(frame: frame)
        self.bgColors = bgColors
        self.lineWidth = lineWidth
        self.progressColors = progressColors
        self.bgLocations = bgLocations
        self.progressLocations = progressLocations
        
        draw(frame)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    
    override func draw(_ rect: CGRect) {
        super.draw(rect)
        
        self.bgGradientLayer.removeFromSuperlayer()
        self.progressGradientLayer.removeFromSuperlayer()
        
        self.bgGradientLayer.frame = self.bounds
        self.bgGradientLayer.colors = self.bgColors
        self.bgGradientLayer.locations = self.bgLocations as [NSNumber]
        self.bgGradientLayer.startPoint = CGPoint(x: 0, y: 0)
        self.bgGradientLayer.endPoint = CGPoint(x: 0, y: 1)
        
        self.layer.addSublayer(self.bgGradientLayer)
                        
        let center: CGPoint = CGPoint(x: rect.size.width/2, y: rect.size.height/2)
        //畫貝塞爾曲線
        let bezierPath = UIBezierPath(arcCenter: center, radius: (rect.size.width - self.lineWidth)/2, startAngle: CGFloat(-0.5 * Double.pi), endAngle: CGFloat(1.5 * Double.pi), clockwise: true)
        
        self.bgLayer.frame = self.bounds
        self.bgLayer.lineWidth = self.lineWidth
        self.bgLayer.fillColor = UIColor.clear.cgColor
        self.bgLayer.strokeColor = UIColor.red.cgColor
        self.bgLayer.opacity = 0.2
        
        self.bgLayer.lineCap = .round //設(shè)置畫筆
        self.bgLayer.path = bezierPath.cgPath //將曲線添加到layer層
        //修改漸變layer層的遮罩，關(guān)鍵代碼
        self.bgGradientLayer.mask = self.bgLayer
                
        self.progressGradientLayer.frame = self.bounds
        self.progressGradientLayer.colors = self.progressColors
        self.progressGradientLayer.locations = self.progressLocations as [NSNumber]
        self.progressGradientLayer.startPoint = CGPoint(x: 0, y: 0)
        self.progressGradientLayer.endPoint = CGPoint(x: 0, y: 1)
        
        self.layer.addSublayer(self.progressGradientLayer)
        
        self.progressLayer.frame = self.bounds
        self.progressLayer.lineWidth = self.lineWidth
        self.progressLayer.fillColor = UIColor.clear.cgColor
        self.progressLayer.strokeColor = UIColor.red.cgColor
        
        self.progressLayer.lineCap = .round //設(shè)置畫筆
        self.progressLayer.path = bezierPath.cgPath
        //修改漸變layer層的遮罩，關(guān)鍵代碼
        self.progressGradientLayer.mask = self.progressLayer
    }
    
    
    public func setProgress(_ progress: Double, animated: Bool = false, duration: Double = 1.0) {
        self.progress = progress
        if animated {
            let animation = CABasicAnimation(keyPath: "strokeEnd")
            animation.duration = duration
            animation.fromValue = 0
            animation.toValue = progress
            self.progressLayer.add(animation, forKey: nil)
            CATransaction.begin()
            CATransaction.setDisableActions(true)
            // 在這里進(jìn)行屬性更改，例如設(shè)置 progressLayer 的 strokeEnd
            self.progressLayer.strokeEnd = self.progress
            CATransaction.commit()
        } else {
            CATransaction.begin()
            CATransaction.setDisableActions(true)
            // 在這里進(jìn)行屬性更改，例如設(shè)置 progressLayer 的 strokeEnd
            self.progressLayer.strokeEnd = self.progress
            CATransaction.commit()
        }
    }
    
    //MARK: - lazy load -
        
    private lazy var bgLayer: CAShapeLayer = {
        let layer = CAShapeLayer()
        return layer
    }()
    
    private lazy var bgGradientLayer: CAGradientLayer = {
        let layer = CAGradientLayer()
        return layer
    }()
    
    private lazy var progressLayer: CAShapeLayer = {
        let layer = CAShapeLayer()
        layer.strokeEnd = 0.0
        return layer
    }()
    
    private lazy var progressGradientLayer: CAGradientLayer = {
        let layer = CAGradientLayer()
        return layer
    }()
    
}