arrays - 在 Swift 中将 NSArray 转换为 Array 会对数组值产生 nil

Question

我遇到了一些我认为很简单的问题，但不知何故我想不出任何方法来解决它。它只是将 NSArray 转换为数组，我认为我用这段代码做得很好:

func getTrainingSubCategories(completion: @escaping(Result<[TrainingSubCategory], GetError>) -> Void){
    let dataTask = URLSession.shared.dataTask(with: resourceURL){data, _, _ in
        guard let jsonData = data else {
            completion(.failure(.trainingCategoriesNoDataAvailable))
            return
        }
        do{
            let parsedData = try JSONSerialization.jsonObject(with: jsonData) as! [String: Any]
            for (key, value) in parsedData {
                if key == "categories" {
                    if let categoriesDictionary: [[String: Any]] = value as? [[String: Any]]{
                        for categoryDictionary in categoriesDictionary{
                            for (key, value) in categoryDictionary{
                                if key == "sub_categories" {
                                    print("1st Type => \(type(of: value)) Value => \(value)")
                                    print("2nd Type => \(type(of: value as? Array<TrainingSubCategory>)) Value => \(value as? Array<TrainingSubCategory>)")
//                                        guard let subCategoryValue = value as? Array<TrainingSubCategory> else{
//                                            fatalError("Error in casting value to array of trainingsubcategory")
//                                        }
                                }
                            }
                        }
                    }
                }
            }
        }catch {
            completion(.failure(.trainingSubCategoriesCannotProcessData))
        }

    }
    dataTask.resume()
}

但控制台会否则记录:

1st Value => (
        {
        "category_id" = 1;
        "company_id" = 50;
        "created_at" = "2019-11-07 00:58:37";
        "deleted_at" = "<null>";
        id = 1;
        name = Advertisement;
        "updated_at" = "2019-11-07 00:58:37";
    },
        {
        "category_id" = 1;
        "company_id" = 50;
        "created_at" = "<null>";
        "deleted_at" = "<null>";
        id = 3;
        name = Sales;
        "updated_at" = "2019-11-10 23:28:30";
    }
)
2nd Value => nil
1st Value => (
        {
        "category_id" = 2;
        "company_id" = 50;
        "created_at" = "2019-11-07 19:58:07";
        "deleted_at" = "<null>";
        id = 6;
        name = Inventory;
        "updated_at" = "2019-11-07 19:58:07";
    }
)
2nd Value => nil
1st Value => (
        {
        "category_id" = 3;
        "company_id" = 50;
        "created_at" = "2019-11-10 21:24:22";
        "deleted_at" = "<null>";
        id = 9;
        name = "Human Resource";
        "updated_at" = "2019-11-10 21:24:22";
    }
)
2nd Value => nil

我在这里遗漏了什么吗？我对 Swift 还很陌生，所以我自己实际上并没有太多的猜测。

Answer 1

所以我将返回类型设置为一个 NSDictionary 数组。

func getTrainingSubCategories(completion: @escaping(Result<[NSDictionary], GetError>) -> Void){
    let dataTask = URLSession.shared.dataTask(with: resourceURL){data, _, _ in
        guard let jsonData = data else {
            completion(.failure(.trainingCategoriesNoDataAvailable))
            return
        }
        var trainingSubCategories = [NSDictionary]()
        do{
            let parsedData = try JSONSerialization.jsonObject(with: jsonData) as! [String: Any]
            for (key, value) in parsedData {
                if key == "categories" {
                    if let categoriesDictionary: [[String: Any]] = value as? [[String: Any]]{
                        for categoryDictionary in categoriesDictionary{
                            for (key, value) in categoryDictionary{
                                if key == "sub_categories" {
                                    if let subCategoriesArray: [Any] = value as? [Any] {
                                        for subCategory in subCategoriesArray{
                                            trainingSubCategories.append(subCategory as! NSDictionary)
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
                completion(.success(trainingSubCategories))
            }
        }catch {
            completion(.failure(.trainingSubCategoriesCannotProcessData))
        }
        
    }
    dataTask.resume()
}

我的函数调用与返回看起来像这样:

private func downloadSubCategories(withCompanyID: Int) {
    let trainingCategoriesRequest = GetRequests(endpoint: "getTrainingCategories", id: String(withCompanyID))
    trainingCategoriesRequest.getTrainingSubCategories{result in
        switch result{
        case .success(let trainingSubCategories):
            for counter in 0 ..< trainingSubCategories.count {
                for (key, value) in trainingSubCategories[counter]{
                    print("\(key) => \(value)")
                }
            }
        case .failure(let error):
            print(error)
        }
    }
}

我无需将 NSDictionary 转换为 TrainingSubCategory 即可映射它们。对于您查看这篇文章，我很抱歉，这不是最初问题的答案，而是一种解决方法。 :)