如何让我的 iOS 应用程序与 api 连接

您正在丢弃所有有意义的错误信息，这将使诊断变得困难.如果得到Error个对象，则应返回:

enum WebServiceError: Error {
    case httpError(Data, Int)
}

func getResults(completion: @escaping (Result<[Results], Error>) -> Void) {
    let urlString = "https://www.arbeitnow.com/api/job-board-api"
    guard let url = URL(string: urlString) else {
        completion(.failure(URLError(.badURL)))
        return
    }

    let task = URLSession.shared.dataTask(with: url) { data, response, error in
        guard
            let data = data,
            let response = response as? HTTPURLResponse,
            error == nil
        else {
            completion(.failure(error ?? URLError(.badServerResponse)))
            return
        }

        guard 200 ..< 300 ~= response.statusCode else {
            completion(.failure(WebServiceError.httpError(data, response.statusCode)))
            return
        }

        do {
            let decoder = JSONDecoder()
            decoder.keyDecodingStrategy = .convertFromSnakeCase
            let results = try decoder.decode([Results].self, from: data)
            completion(.success(results.data))
        } catch {
            completion(.failure(error))
        }
    }
    task.resume()
}

所以，这将，

• 如果有URLSession个错误，告诉你错误是什么；
• 如果有一个非2xx状态代码，告诉你代码是什么(如果你想查看，也返回响应的主体)；和
• 如果有解析错误，请告诉您解析错误是什么.

如果没有这样的东西，捕捉到显著的错误信息，你就是在瞎飞.

在本例中，错误在于您正在解析[Results]，但 struct 是一个字典，其键是data，其值是[Results].您缺少一个包含[Results]的字典对象.

struct ResponseObject: Decodable {
    let data: [Posting]
    let links: Links
    let meta: Meta
}

struct Posting: Decodable {
    let slug, companyName, title, description: String
    let remote: Bool
    let url: String
    let tags, jobTypes: [String]
    let location: String
    let createdAt: Int
}

struct Links: Decodable {
    let first: URL?
    let last: URL?
    let prev: URL?
    let next: URL?
}

struct Meta: Decodable {
    let currentPage: Int
    let path: URL
    let perPage: Int
    let from: Int
    let to: Int
    let terms: String
    let info: String
}

func getResults(completion: @escaping (Result<[Posting], Error>) -> Void) {
    let urlString = "https://www.arbeitnow.com/api/job-board-api"
    guard let url = URL(string: urlString) else {
        completion(.failure(URLError(.badURL)))
        return
    }

    let task = URLSession.shared.dataTask(with: url) { data, response, error in
        guard
            let data = data,
            let response = response as? HTTPURLResponse,
            error == nil
        else {
            completion(.failure(error ?? URLError(.badServerResponse)))
            return
        }

        guard 200 ..< 300 ~= response.statusCode else {
            completion(.failure(WebServiceError.httpError(data, response.statusCode)))
            return
        }

        do {
            let decoder = JSONDecoder()
            decoder.keyDecodingStrategy = .convertFromSnakeCase
            let results = try decoder.decode(ResponseObject.self, from: data)
            completion(.success(results.data))
        } catch {
            completion(.failure(error))
        }
    }
    task.resume()
}