ios - swift 中的嵌套重复循环

Question

我试图在 swift 中解析一个嵌套的迭代循环我从 Web 服务获得以下格式的响应

{
    "categories": [{
        "name": "Default Category",
        "id": "default_category",
        "children": [{
            "uuid": "783f491fef5041438fb7a2c3bf6a3650",
            "name": "Accessories",
            "children": [{
                "uuid": "d21b4491ff784a9bae88de279b99fac3",
                "name": "All Accessories",
                "children": [{
                        "uuid": "2b1a23c4107844ad8a7afc1b324d0ffd",
                        "name": "Belts",
                        "children": [{
                                "uuid": "2b1a23c4107844ad8a7afc1b324d0ffd",
                                "name": "Belts",
                                "children": []

                            },
                            {
                                "uuid": "2b1a23c4107844ad8a7afc1b324d0ffd",
                                "name": "Belts",
                                "children": []
                            }
                        ]
                    },
                    {
                        "uuid": "a1c2a64c36c2461cad3d5f850e4fd0f5",
                        "name": "Hats",
                        "children": []
                    },
                    {
                        "uuid": "8f26bc764b8342feaa0cb7f3b96adcae",
                        "name": "Scarves",
                        "children": []
                    },
                    {
                        "uuid": "aa1116d1a0254ecea836cc6b32eeb9e0",
                        "name": "Sunglasses",
                        "children": []
                    },
                    {
                        "uuid": "9d7033233e8f47eaa69eb1aaf2e98cdd",
                        "name": "Watches",
                        "children": []
                    }
                ]
            }]
        }],
        "uuid": "6a23415771064e7aaad59f84f8113561"
    }]
}

在类别中，有一个“children”键，它又可以包含另一个 child 等等。我想在子键内不断循环，直到子键为空，然后将最后一个子键插入数据库。

下面是我完成的代码

     for currentCategory in mainCategories {


    // guard against if there are child categories
            guard var children = currentCategory.children, children.count > 0 else {
                //  Save the context
                self.coreData.saveStore()
                continue
            }                    
            for thisChildCategory in children {

                if thisChildCategory.children?.count > 0 {
                    for innerChildCategory in thisChildCategory.children! {
                        print("innerChildCategory name \(String(describing: innerChildCategory.name))")
                    }
                }

                if let child = thisChildCategory.children {
                    children = child
                }

                //  Create new object
                if let currentChildCategory  = self.coreData.insertNewObject(CoreDataEntities.BijouCategories.rawValue,
                    keyValues: ["id" : thisChildCategory.id! as Optional<AnyObject>,
                        "uuid" : thisChildCategory.uuid as Optional<AnyObject>,
                        "name" : thisChildCategory.name! as Optional<AnyObject>,
                        "gender" : thisChildCategory.gender as Optional<AnyObject>!,
                        "active" : NSNumber(value: false)]) as? BijouCategories {

                    //  Set as parent category
                    currentChildCategory.parentCategory = parentCategory


                    //  Save the context
                    self.coreData.saveStore()

                }
            }

        }

但这并没有保存数据库中的所有最后一个子类别。

Answer 1

swift 4

您应该让 Swift 4 的 codable 为您完成这项工作。

您可以使用以下类作为结构，但我发现如果您计划编辑数据，使用类会更好。

class Categories: Codable {
     var categories: [CategoryItems]
}

class CategoryItems: Codable {
    var name: String?
    var id: String?
    var uuid: String?
    var children: [CategoryItems]?

required init(from decoder: Decoder) throws {
    var container = try decoder.container(keyedBy: CodingKeys.self)
    name = try container.decodeIfPresent(String.self, forKey: CodingKeys.name)
    id = try container.decodeIfPresent(String.self, forKey: CodingKeys.id)
    uuid = try container.decodeIfPresent(String.self, forKey: CodingKeys.uuid)
    children = try container.decodeIfPresent([CategoryItems].self, forKey: CodingKeys.children)
    if children != nil, children!.count == 0 {
        children = nil
    }
}

您可以在此处看到我们添加了创建具有 CategoryItems 数组的根级类“Categories”。 CategoryItems 中包含所有可能的值，但数组中的每个项目可能具有也可能不具有所有可能的值，因此它们是可选的。重要的是 child ，这是可选的。然后在所需的 init 中，如果在解码时键值对可用，我们只设置可选值。如果项目为零，我还将子项设置为 nil，这是可选的，但在稍后执行 if 语句时会有所帮助。

然后使用以下代码使用这些可编码类解码您的 json。

func decode(jsonData data: Data) {
    let decoder = JSONDecoder()
    do {
        let decoded = try decoder.decode(Categories.self, from: data)
    }
    catch let error as NSError {
        print("JSON Decode error = ", error)
    }
}

如果你想做一个快速测试，看看你是否达到了我所做的更深层次的 child 水平，你可以简单地在解码变量上运行以下命令。

for i in decoded.categories.first!.children!.first!.children!.first!.children!.first!.children! {
     print(i.name)
     print(i.uuid)
}