WWScratchCard

import UIKit
import WWScratchCard

final class ViewController: UIViewController {

    @IBOutlet weak var label: UILabel!
    @IBOutlet weak var scratchCard: WWScratchCardView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        test()
    }
}

// MARK: - WWScratchCardDelegate
extension ViewController: WWScratchCardDelegate {
    
    func scratchBegan(point: CGPoint) {}
    
    func scratchMoved(progress: Float) {
        let percent = String(format: "%.1f", progress * 100)
        label.text = "\(percent)%"
    }
    
    func scratchEnded(point: CGPoint) {}
}

// MARK: - 小工具
private extension ViewController {
    
    func test() {
        
        guard let couponImage = UIImage(named: "Desktop.png"),
              let maskImage = UIImage(named: "Gray.png")
        else {
            return
        }
        
        scratchCard.setting(delegate: self, couponImage: couponImage, maskImage: maskImage, contentMode: .scaleToFill)
        
        DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
            self.scratchCard.restart(couponImage: couponImage, maskImage: maskImage, contentMode: .scaleToFill)
            self.label.text = "0.0 %"
        }
    }
}