import UIKit

public enum UIViewMask {
    case cornerRadius(CGFloat)
    case bezierPath(UIBezierPath)
    case cgPath(CoreGraphics.CGPath)
    case image(UIImage)
    case cgImage(CoreGraphics.CGImage)
    case view(UIView)
}

public final class FinalizedObjCAssociated<T>: NSObject {
    public typealias AssociatedValue = T
    public var value: AssociatedValue
    
    public init(_ value: AssociatedValue) {
        self.value = value
        super.init()
    }
}

public class OpenObjCAssociated<T>: NSObject {
    public typealias AssociatedValue = T
    public var value: AssociatedValue
    
    public init(_ value: AssociatedValue) {
        self.value = value
        super.init()
    }
}

// We create a value with 30 corner radius.
let value = UIViewMask.cornerRadius(30)

// And then create an open associated object,
let openAssociated = OpenObjCAssociated(value)

// and a finalized associated object.
let finalizedAssociated = FinalizedObjCAssociated(value)

// The open associated object's value is what we just have set.
print(openAssociated.value)

// But the finalized assocaited object's value is 0.
print(finalizedAssociated.value)