在正常项目中，需要将模型model本地化存储就必须用到解归档，解归档需要将模型中的所有的属性都一一写一遍非常麻烦，可以通过runtime快速完成自动解归档操作。

    // 归档
    func encode(with aCoder: NSCoder) {
        var c = self.classForCoder
        while c != NSObject.self {
            var count: UInt32 = 0
            // 获得class中所有属性
            guard let ivars = class_copyIvarList(c, &count) else { return }
            for i in 0..<count {
                let key = NSString(utf8String: ivar_getName(ivars[Int(i)])!)! as String
                let value = self.value(forKey: key)
                aCoder.encode(value, forKey: key)
            }
            // 获得父类
            c = c.superclass()!
            // 释放
            free(ivars)
        }
    }

    // 解归档
    required init?(coder aDecoder: NSCoder) {
        super.init()
        var c = self.classForCoder
        while c != NSObject.self {
            var count: UInt32 = 0
            // 获得class中所有属性
            guard let ivars = class_copyIvarList(c, &count) else { return }
            for i in 0..<count {
                let key = NSString(utf8String: ivar_getName(ivars[Int(i)])!)! as String
                let value = aDecoder.decodeObject(forKey: key)
                self.setValue(value, forKey: key)
            }
            // 获得父类
            c = c.superclass()!
            // 释放
            free(ivars)
        }
    }