通过该值中的特定对象过滤掉对象

Question

所以我有一个对象列表让我们说运动鞋。我通过解析JSON数据来获取这些对象。下面是我用来执行该任务的模型类。

@objcMembers class SneakerInfoTemp: Object, Decodable {
//    dynamic var id = UUID().uuidString

    //list of dynamic properties that will be deserialized from the json and then passed into realm
    dynamic var brand: String?
    dynamic var category: String?
    dynamic var colorway: String?
    dynamic var currentdescription: String?
    dynamic var designer: String?
    dynamic var imagesrc: String?
    dynamic var maincolor: String?
    dynamic var name: String?
    dynamic var nickname: String?
    dynamic var price: String?
    dynamic var productlink: String?
    dynamic var productlinkhref: String?
    dynamic var releasedate: String?
    dynamic var silhouette: String?
    dynamic var technology: String?
    dynamic var webscraperorder: String?
    dynamic var webscraperstarturl: String?

    enum CodingKeys: String, CodingKey {
        case brand, category, colorway, designer, imagesrc, maincolor, name, nickname, price, productlink, productlinkhref, releasedate, silhouette, technology,webscraperorder,webscraperstarturl,currentdescription
    }

    required init(from decoder: Decoder) throws
    {
        let container = try decoder.container(keyedBy: CodingKeys.self)

        //sneaker information that will be decoded
        //made optional due to the fact that some fields don't exist with every shoe
        brand = try? container.decode(String.self, forKey: .brand)
        category = try? container.decode(String.self, forKey: .category)
        colorway = try? container.decode(String.self, forKey: .colorway)
        currentdescription = try? container.decode(String.self, forKey: .currentdescription)
        designer = try? container.decode(String.self, forKey: .designer)
        imagesrc = try? container.decode(String.self, forKey: .imagesrc)
        maincolor = try? container.decode(String.self, forKey: .maincolor)
        name = try? container.decode(String.self, forKey: .name)
        nickname = try? container.decode(String.self, forKey: .nickname)

        price = try? container.decode(String.self, forKey: .price)
        productlink = try? container.decode(String.self, forKey: .productlink)
        productlinkhref = try? container.decode(String.self, forKey: .productlinkhref)
        releasedate = try? container.decode(String.self, forKey: .releasedate)
        silhouette = try? container.decode(String.self, forKey: .silhouette)
        technology = try? container.decode(String.self, forKey: .technology)
        webscraperorder = try? container.decode(String.self, forKey: .webscraperorder)
        webscraperstarturl = try? container.decode(String.self, forKey: .webscraperstarturl)
        super.init()
    }


    required init()
    {
        super.init()
    }

    override class func primaryKey() -> String? {
        return "name"
    }

    required init(value: Any, schema: RLMSchema)
    {
        super.init(value: value, schema: schema)
    }

    required init(realm: RLMRealm, schema: RLMObjectSchema)
    {
        super.init(realm: realm, schema: schema)
    }


}

当一切都说完了，我得到一个对象列表。手头的问题是一些对象是重复的。我试图使用一个集来删除它们，但集合无法区分对象之间的区别。我有点想要获取这个对象列表并将它们添加到基于某些属性的集合中，让我们说出名称

我想做这样的事情

   let objectSet = Set((sneakersTemp.sneakers?.brands?.adidas.map { $0.name })!)
        print(objectSet.count)

它返回所有唯一的名称，但无论如何我也可以获得所有独特的对象。

Answer 1

要使用Set删除重复项，类型应符合Hashable。

为简化起见，我们假设SneakerInfoTemp类的定义如下：

class SneakerInfoTemp {
    let name: String
    let price: Double

    init(name: String, price: Double) {
        self.name = name
        self.price = price
    }
}

让我们遵守必要的协议：

extension SneakerInfoTemp: Equatable {
    static func == (lhs: SneakerInfoTemp, rhs: SneakerInfoTemp) -> Bool {
        return lhs.name == rhs.name
    }
}

extension SneakerInfoTemp: Hashable {
    func hash(into hasher: inout Hasher) {
        hasher.combine(name)
    }
}

所以给了一系列运动鞋：

var array = [SneakerInfoTemp(name: "a", price: 1),
             SneakerInfoTemp(name: "b", price: 2),
             SneakerInfoTemp(name: "a", price: 3),
]

您可以使用Set创建一组唯一元素：

let set = Set(array)

Answer 2

使用.filter而不是.map。试试这个

let array : [Obj] = sneakersTemp.sneakers?.brands?.adidas
let filtered = filterUnique(array: array)

其中Obj - sneakersTemp.sneakers?.brands?.adidas数组的类/结构（或其超类名称：String）

func filterUnique(array : [Obj]) -> [Obj] {
    var filtered : [String] = []
    let objectSet = array.filter({ obj -> Bool in
        if filtered.contains(obj.name) {
            return false
        }
        filtered.append(obj.name)
        return true
    })
    print(objectSet.count)
}