Swift 成员变量的get/set

import UIKitclass Question: NSObject {    var answer: String!    var icon: String!    var title: String!    var options: [String]!    // 自定义 get、set    var image: UIImage {        get {            return UIImage(named: self.icon)!        }        set {            self.image = newValue        }    }    // 懒加载    lazy private var questions: [AnyObject] = {        // 例如：        return ["quetion1", "quetion2", "quetion3"]    }()    // 指定初始化    init(data: [String : AnyObject]) {        super.init()        self.setValuesForKeysWithDictionary(data)    }}