UIView shimmer effect with direction Swift 5

We are going to create a UIView Extension to add shimmer effect of UIView and the class derived from it like UILable, UIImageView, UIButton etc.
Let’s add below UIView Extension in your project.
import UIKit

extension UIView {
  
  // ->1
  enum Direction: Int {
    case topToBottom = 0
    case bottomToTop
    case leftToRight
    case rightToLeft
  }
  
  func startShimmeringAnimation(animationSpeed: Float = 1.4,
                                direction: Direction = .leftToRight,
                                repeatCount: Float = MAXFLOAT) {
    
    // Create color  ->2
    let lightColor = UIColor(displayP3Red: 1.0, green: 1.0, blue: 1.0, alpha: 0.1).cgColor
    let blackColor = UIColor.black.cgColor
    
    // Create a CAGradientLayer  ->3
    let gradientLayer = CAGradientLayer()
    gradientLayer.colors = [blackColor, lightColor, blackColor]
    gradientLayer.frame = CGRect(x: -self.bounds.size.width, y: -self.bounds.size.height, width: 3 * self.bounds.size.width, height: 3 * self.bounds.size.height)
    
    switch direction {
    case .topToBottom:
      gradientLayer.startPoint = CGPoint(x: 0.5, y: 0.0)
      gradientLayer.endPoint = CGPoint(x: 0.5, y: 1.0)
      
    case .bottomToTop:
      gradientLayer.startPoint = CGPoint(x: 0.5, y: 1.0)
      gradientLayer.endPoint = CGPoint(x: 0.5, y: 0.0)
      
    case .leftToRight:
      gradientLayer.startPoint = CGPoint(x: 0.0, y: 0.5)
      gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.5)
      
    case .rightToLeft:
      gradientLayer.startPoint = CGPoint(x: 1.0, y: 0.5)
      gradientLayer.endPoint = CGPoint(x: 0.0, y: 0.5)
    }
    
    gradientLayer.locations =  [0.35, 0.50, 0.65] //[0.4, 0.6]
    self.layer.mask = gradientLayer
    
    // Add animation over gradient Layer  ->4
    CATransaction.begin()
    let animation = CABasicAnimation(keyPath: "locations")
    animation.fromValue = [0.0, 0.1, 0.2]
    animation.toValue = [0.8, 0.9, 1.0]
    animation.duration = CFTimeInterval(animationSpeed)
    animation.repeatCount = repeatCount
    CATransaction.setCompletionBlock { [weak self] in
      guard let strongSelf = self else { return }
      strongSelf.layer.mask = nil
    }
    gradientLayer.add(animation, forKey: "shimmerAnimation")
    CATransaction.commit()
  }
  
  func stopShimmeringAnimation() {
    self.layer.mask = nil
  }
  
}

As we can see, above function is taking three parameters and all are optional:
animationSpeed: How fast you want the shimmer
direction: Direction of the shimmer effect
repeatCount: This is repeat count of the animation
1: This is the direction of the shimmer effect
2: Colors for the shimmer, you can change as per your uses
3: We are creating a CAGradientLayer here, if you want to know more details about CAGradientLayer then check here.
4: Adding CABasicAnimation animation over gradient layer.
Now just write below one line of code to start shimmering
self.myView.startShimmeringAnimation()

Shimmer direction

If you want to change only the direction fo the shimmer then write below code
self.myView.startShimmeringAnimation(direction: .topToBottom)

Animation speed and repeat count

If you want to control the animation speed and repeat count then just write below code.
self.myView.startShimmeringAnimation(animationSpeed: 1.4, direction: .bottomToTop, repeatCount: 1000)


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