swift 跑马灯

import UIKit

class MarqueeText: UIView {
    public var text: String? {
        willSet {
            nameLabel?.text = newValue
            setNeedsLayout()
        }
    }

    public var textColor: UIColor = UIColor.colorWithHexString(color: "ffffff") {
        willSet {
            nameLabel?.textColor = newValue
        }
    }

    public var textFont: UIFont = .systemFont(ofSize: 14, weight: .medium) {
        willSet {
            nameLabel?.font = newValue
        }
    }

    private weak var displayLink: CADisplayLink?

    private var duration: TimeInterval = 0

    /// 是否向左滚动标记
    private var isLeft: Bool = true

    /// 是否需要滚动标记
    private var isCanRun: Bool = true

    private weak var nameLabel: UILabel?
    private weak var scrollView: UIScrollView?
    private weak var leftGlassLayer: CAGradientLayer?
    private weak var rightGlassLayer: CAGradientLayer?

    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = UIColor.clear
        initSubviews()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        displayLink?.isPaused = true
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        if isCanRun {
            displayLink?.isPaused = false
        }
    }

    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
        if isCanRun {
            displayLink?.isPaused = false
        }
    }

    deinit {
        self.displayLink?.invalidate()
        self.displayLink = nil
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        let textSize = nameLabel?.text?.strwidth(str: (nameLabel?.text)!, font: 14)
        let margin: CGFloat = 0
        let textWith = textSize!.width + margin * 2
        scrollView?.frame = bounds
        scrollView?.backgroundColor = UIColor.clear
        scrollView?.contentSize = CGSize(width: 0, height: textWith)
        nameLabel?.frame = CGRect(x: 0, y: 0, width: textWith, height: textSize!.height)
        duration = 0
        nameLabel?.backgroundColor = UIColor.clear
        isCanRun = textWith > width
        displayLink?.isPaused = width >= textWith

        leftGlassLayer?.isHidden = width >= textWith
        rightGlassLayer?.isHidden = width >= textWith
        leftGlassLayer?.frame = CGRect(x: 0, y: 0, width: 25, height: height)
        rightGlassLayer?.frame = CGRect(x: width - 25, y: 0, width: 25, height: height)
    }

    private func initSubviews() {
        let scrollView = UIScrollView()
        scrollView.isUserInteractionEnabled = false
        scrollView.showsVerticalScrollIndicator = false
        scrollView.showsHorizontalScrollIndicator = false
        addSubview(scrollView)
        self.scrollView = scrollView

        let nameLabel = UILabel()
        nameLabel.textAlignment = .center
        nameLabel.font = textFont
        nameLabel.textColor = textColor
        scrollView.addSubview(nameLabel)
        self.nameLabel = nameLabel

        let displayLink = CADisplayLink(target: self, selector: #selector(timerEvent))
        displayLink.add(to: RunLoop.current, forMode: RunLoop.Mode.common)
        displayLink.isPaused = true
        self.displayLink = displayLink

        let leftGlassLayer = CAGradientLayer()
        leftGlassLayer.startPoint = .zero
        leftGlassLayer.endPoint = CGPoint(x: 1, y: 0)
//        leftGlassLayer.colors = [UIColor.colorWithHexString(color: "6DD781").cgColor, UIColor.colorWithHexString(color: "6DD781", alpha: 0).cgColor]
        leftGlassLayer.colors = [UIColor.clear.cgColor]
        layer.addSublayer(leftGlassLayer)
        self.leftGlassLayer = leftGlassLayer

        let rightGlassLayer = CAGradientLayer()
        rightGlassLayer.startPoint = .zero
        rightGlassLayer.endPoint = CGPoint(x: 1, y: 0)
//        rightGlassLayer.colors = [UIColor.colorWithHexString(color: "6DD781", alpha: 0).cgColor, UIColor.colorWithHexString(color: "6DD781").cgColor]
        rightGlassLayer.colors = [UIColor.clear.cgColor]
        layer.addSublayer(rightGlassLayer)
        self.rightGlassLayer = rightGlassLayer
    }

    var i = 0
    @objc private func timerEvent() {
        if duration == 0 {
            if i == 0 {
                DispatchQueue.main.asyncAfter(deadline: .now() + 2.0) { [self] in
                    abcd()
                    i = 0
                }
                i = 1
            }

        } else {
            abcd()
        }
    }

    /// 定时器事件
    func abcd() {
        let maxWith = (nameLabel?.width ?? 0) - width + 40
        let scale: TimeInterval = 0.3
        if duration < 0 {
            isLeft = false
            duration += scale
        } else if duration >= 0 && duration <= TimeInterval(maxWith) {
            if isLeft {
                duration -= scale
            } else {
                duration += scale
            }
        } else {
            isLeft = true
            duration = 0
        }

        scrollView?.setContentOffset(CGPoint(x: duration, y: 0), animated: false)
    }
}
/**
 其中 leftGlassLayer 和 rightGlassLayer 是滚动是两边的文字模糊效果的遮罩层；maxWith 为 Label 在 ScrollView 上的x轴方向上的最大滚动宽度；在不超过最大滚动宽度时，进行 self.duration += scale 操作即向右运动；超过最大滚动宽度时宽度，进行 self.duration -= scale 操作即向左运动；调整 scale 大小可以控制滚动的快慢。

 作者：苍眸之宝宝
 链接：https://www.jianshu.com/p/913d04808c34
 来源：简书
 著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。
 */

使用

   comName_LbBgView.addSubview(MarqueeTextView)
        MarqueeTextView.snp.makeConstraints { (make) in
            make.top.bottom.right.leading.equalToSuperview()
        }