save/restore abstract objects

archive-unarchive-1.swift

/*
	This sample code shows the problem of archive and unarchive abstruct objects. Please see `TODO` keyword
	and make this Contents class to save and load shape objects.
*/

import Foundation
import CoreGraphics

protocol Shape {
}

class Circle: Shape {
	var center: CGPoint
	var radius: CGFloat
	init(center: CGPoint, radius: CGFloat) {
		self.center = center
		self.radius = radius
	}
}

class Rectangle: Shape {
	var origin: CGPoint
	var size: CGSize
	init(origin: CGPoint, size: CGSize) {
		self.origin = origin
		self.size = size
	}
}

class RoundedRectangle: Rectangle {
	var cornerRadius: CGFloat
	init(origin: CGPoint, size: CGSize, cornerRadius: CGFloat) {
		self.cornerRadius = cornerRadius
		super.init(origin: origin, size: size)
	}
}

class Contens {
	var shapes: [Shape]
	init(shapes: [Shape]) {
		self.shapes = shapes
	}
	init?(binary: Data) {
		// TODO: archive shapes to binary
		fatalError()
	}
	func binary() -> Data {
		// TODO: unarchive all shpes from binary
		fatalError()
	}
}