你已经很接近了......只要做一些改变就能让你达到你想要的目的。
如果你有一个UILabel和一个UIImageView（或普通的UIView）限制在标签的右边缘，你应该能够定位你的CAReplicatorLayer，而不必担心“屏幕大小”。
看看我是如何修改你的代码的：

// baseline = to put the bottom of the dots at the baseline of the text in the label
// dotXOffset = gap between end of label and first dot
// dotSize = dot width and height
// dotSpacing = gap between dots
func showAnimatingDotsInImageView(dotsView: UIView, baseline: CGFloat, dotXOffset: CGFloat, dotSize: CGFloat, dotSpacing: CGFloat) {
    let lay = CAReplicatorLayer()
    let bar = CALayer()
    bar.frame = CGRect(x: dotXOffset, y: baseline - dotSize, width: dotSize, height: dotSize)
    bar.cornerRadius = bar.frame.width / 2  // we want round dots
    bar.backgroundColor = UIColor.black.cgColor
    lay.addSublayer(bar)
    lay.instanceCount = 3   //How many instances / objs do you want to see
    lay.instanceTransform = CATransform3DMakeTranslation(dotSpacing, 0, 0) //1st arg is the spacing between the instances
    let anim = CABasicAnimation(keyPath: #keyPath(CALayer.opacity))
    anim.fromValue = 1.0
    anim.toValue = 0.2
    anim.duration = 1
    anim.repeatCount = .infinity
    bar.add(anim, forKey: nil)
    lay.instanceDelay = anim.duration / Double(lay.instanceCount)
    dotsView.layer.addSublayer(lay)    // add to the view
}

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下面是一个完整的例子：

class SimpleViewController: UIViewController {
    
    let testLabel = UILabel()
    let testDotsView = UIView()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        testLabel.font = .systemFont(ofSize: 24.0)
        
        testLabel.text = "Retrieving boxes"
        
        // so we can see the label frame
        testLabel.backgroundColor = .cyan
        
        testLabel.translatesAutoresizingMaskIntoConstraints = false
        testDotsView.translatesAutoresizingMaskIntoConstraints = false
        
        view.addSubview(testLabel)
        view.addSubview(testDotsView)
        
        // always respect safe area
        let g = view.safeAreaLayoutGuide
        
        NSLayoutConstraint.activate([
            
            // let's constrain the label
            //  40-pts from Leading
            //  40-pts from Bottom
            testLabel.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 40.0),
            testLabel.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -40.0),
            
            // constrain dots view to
            //  Top of label
            //  Trailing of label
            testDotsView.topAnchor.constraint(equalTo: testLabel.topAnchor),
            testDotsView.leadingAnchor.constraint(equalTo: testLabel.trailingAnchor, constant: 0.0),
            // dots image view Width and Height can be 0 (we can draw the layer outside the bounds)
            testDotsView.heightAnchor.constraint(equalToConstant: 0.0),
            testDotsView.widthAnchor.constraint(equalToConstant: 0.0),
            
        ])
        
        // get the label font's baseline y-value
        let bl: CGFloat = testLabel.font.ascender
        showAnimatingDotsInImageView(dotsView: testDotsView, baseline: bl, dotXOffset: 4.0, dotSize: 4.0, dotSpacing: 8.0)
    }
    
    // baseline = to put the bottom of the dots at the baseline of the text in the label
    // dotXOffset = gap between end of label and first dot
    // dotSize = dot width and height
    // dotSpacing = gap between dots
    func showAnimatingDotsInImageView(dotsView: UIView, baseline: CGFloat, dotXOffset: CGFloat, dotSize: CGFloat, dotSpacing: CGFloat) {
        let lay = CAReplicatorLayer()
        let bar = CALayer()
        bar.frame = CGRect(x: dotXOffset, y: baseline - dotSize, width: dotSize, height: dotSize)
        bar.cornerRadius = bar.frame.width / 2  // we want round dots
        bar.backgroundColor = UIColor.black.cgColor
        lay.addSublayer(bar)
        lay.instanceCount = 3   //How many instances / objs do you want to see
        lay.instanceTransform = CATransform3DMakeTranslation(dotSpacing, 0, 0) //1st arg is the spacing between the instances
        let anim = CABasicAnimation(keyPath: #keyPath(CALayer.opacity))
        anim.fromValue = 1.0
        anim.toValue = 0.2
        anim.duration = 1
        anim.repeatCount = .infinity
        bar.add(anim, forKey: nil)
        lay.instanceDelay = anim.duration / Double(lay.instanceCount)
        dotsView.layer.addSublayer(lay)    // add to the view
    }

}

型

编辑-在回应“克里山库马尔”评论.

要让动画在从后台返回时继续，您需要添加通知观察器。
对于“动画点”视图，使用自定义的UIView子类要容易得多，所以这里有一个简单的例子：

class DotsView: UIView {
    
    // baseline = to put the bottom of the dots at the baseline of the text in the label
    // dotXOffset = gap between end of label and first dot
    // dotSize = dot width and height
    // dotSpacing = gap between dots

    public var baseline: CGFloat = 0
    public var dotXOffset: CGFloat = 4.0
    public var dotSize: CGFloat = 4.0
    public var dotSpacing: CGFloat = 8.0

    private let lay = CAReplicatorLayer()
    private let bar = CALayer()

    override init(frame: CGRect) {
        super.init(frame: frame)
        commonInit()
    }
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        commonInit()
    }
    func commonInit() {
        lay.addSublayer(bar)
        layer.addSublayer(lay)
    }
    public func beginAnimating() {
        bar.frame = CGRect(x: dotXOffset, y: baseline - dotSize, width: dotSize, height: dotSize)
        // we want round dots
        bar.cornerRadius = bar.frame.width / 2.0
        bar.backgroundColor = UIColor.black.cgColor
        //How many instances / objs we want to see
        lay.instanceCount = 3
        //1st arg is the spacing between the instances
        lay.instanceTransform = CATransform3DMakeTranslation(dotSpacing, 0, 0)
        let anim = CABasicAnimation(keyPath: #keyPath(CALayer.opacity))
        anim.fromValue = 1.0
        anim.toValue = 0.2
        anim.duration = 1
        anim.repeatCount = .infinity
        bar.add(anim, forKey: nil)
        // so the dots animate in sequence
        lay.instanceDelay = anim.duration / Double(lay.instanceCount)
    }
    public func stopAnimating() {
        layer.removeAllAnimations()
    }
}

型
以及显示如何使用它的示例控制器，包括当应用程序在前台和后台之间移动时启动/停止动画：

class SimpleViewController: UIViewController {
    
    let testLabel = UILabel()
    
    // custom DotsView
    let testDotsView = DotsView()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        view.backgroundColor = .systemBackground
        
        testLabel.font = .systemFont(ofSize: 24.0)
        
        testLabel.text = "Retrieving boxes"
        
        // so we can see the label frame
        testLabel.backgroundColor = .cyan
        
        testLabel.translatesAutoresizingMaskIntoConstraints = false
        testDotsView.translatesAutoresizingMaskIntoConstraints = false
        
        view.addSubview(testLabel)
        view.addSubview(testDotsView)
        
        // always respect safe area
        let g = view.safeAreaLayoutGuide
        
        NSLayoutConstraint.activate([
            
            // let's constrain the label
            //  40-pts from Leading
            //  40-pts from Bottom
            testLabel.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 40.0),
            testLabel.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -40.0),
            
            // constrain dots view to
            //  Top of label
            //  Trailing of label
            testDotsView.topAnchor.constraint(equalTo: testLabel.topAnchor),
            testDotsView.leadingAnchor.constraint(equalTo: testLabel.trailingAnchor, constant: 0.0),
            // dots image view Width and Height can be 0 (we can draw the layer outside the bounds)
            testDotsView.heightAnchor.constraint(equalToConstant: 0.0),
            testDotsView.widthAnchor.constraint(equalToConstant: 0.0),
            
        ])
        
        // get the label font's baseline y-value
        testDotsView.baseline = testLabel.font.ascender
        
        // use defaults or set values here
        //testDotsView.dotXOffset = 4.0
        //testDotsView.dotSize = 4.0
        //testDotsView.dotSpacing = 8.0
        
        testDotsView.beginAnimating()

        // we want to
        //  Stop the Dots animation when the app goes into the Background, and
        //  Start the Dots animation when the app Enters the Foreground
        NotificationCenter.default.addObserver(self, selector: #selector(myEnterForeground), name: UIApplication.willEnterForegroundNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(myEnterBackground), name: UIApplication.didEnterBackgroundNotification, object: nil)
    }
    
    @objc func myEnterBackground() {
        testDotsView.stopAnimating()
    }
    @objc func myEnterForeground() {
        testDotsView.beginAnimating()
    }
    
}

型

//3点动画完整代码
import Foundation导入UIKit
public class FIOProgressView {

var containerView = UIView()
var progressView = UIView()
var dotsContainerView = UIView()

open class var shared: FIOProgressView {
    struct Static {
        static let instance: FIOProgressView = FIOProgressView()
    }
    return Static.instance
}

open func showProgressView(_ view: UIView) {
    
    containerView.frame = view.frame
    containerView.center = view.center
    containerView.backgroundColor = UIColor(hex: 0xffffff, alpha: 0.3)
    
    progressView.frame = CGRect(x: 0, y: 0, width: 120, height: 40)
    progressView.center = view.center
    progressView.backgroundColor = .clear
    progressView.clipsToBounds = true
    progressView.layer.cornerRadius = 10
    
    dotsContainerView.frame = CGRect(x: 0, y: 0, width: 120, height: 40)
    dotsContainerView.center = CGPoint(x: progressView.bounds.width / 2, y: progressView.bounds.height / 2)
    
    createDots()
    
    progressView.addSubview(dotsContainerView)
    containerView.addSubview(progressView)
    view.addSubview(containerView)
}

private func createDots() {
    let dotSize: CGFloat = 20
    let spacing: CGFloat = 20
    
    for i in 0..<3 {
        let dot = UIView(frame: CGRect(x: CGFloat(i) * (dotSize + spacing), y: 10, width: dotSize, height: dotSize))
        dot.backgroundColor = UIColor(displayP3Red: 92/255, green: 46/255, blue: 126/255, alpha: 1.0)
        dot.layer.cornerRadius = dotSize / 2
        
        dotsContainerView.addSubview(dot)
        animateDot(dot, delay: TimeInterval(i) * 0.3)
    }
}

private func animateDot(_ dot: UIView, delay: TimeInterval) {
      UIView.animate(withDuration: 0.5, delay: delay, options: [.autoreverse, .repeat], animations: {
          dot.transform = CGAffineTransform(scaleX: 0.2, y: 0.2)
      }, completion: nil)
  }

open func hideProgressView() {
    DispatchQueue.main.async {
        self.containerView.removeFromSuperview()
    }
}

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}