使用Alamofire调用TMDB API无法获取数据的求助

核心问题总结 #

你的代码存在三个关键问题导致无法获取并解析TMDB数据：

1. 网络请求URL拼接时变量拼写错误
2. MovieResult结构体未定义CodingKeys，无法正确映射TMDB的蛇形命名JSON字段
3. 回调设置顺序错误，可能导致网络请求完成后无法触发UI更新

具体修复步骤 #

1. 修复NetworkHelper的变量拼写错误 #

在NetworkHelper的requestUrl方法中，你错误地使用了api_key（下划线），但类内定义的API Key变量是apiKey（驼峰），这会导致URL拼接错误，API请求返回权限错误。

修改后的NetworkHelper：

import Foundation
enum HTTPMethods: String{
    case get = "GET"
    case post = "POST"
}
enum ErrorTypes: String, Error{
    case invalidData = "Invalid data"
    case invalidURL = "Invalid url"
    case generalError = "An error happened"
}

class NetworkHelper{
    static let shared = NetworkHelper()
    
    private let baseURL = "https://api.themoviedb.org/3/"
    private let apiKey = "509ef93252a59761a3c353f9ea114de0"
    
    func requestUrl(url: String) -> String {
        return baseURL + url + "?api_key=\(apiKey)" // 修复变量名拼写
    }
}

2. 给MovieResult添加CodingKeys映射 #

TMDB返回的JSON字段是蛇形命名（如genre_ids、backdrop_path），而你的MovieResult属性是驼峰命名，必须通过CodingKeys来映射，否则JSONDecoder无法正确解析字段，导致results数组为空。

修改后的Movie结构体：

import Foundation

// MARK: - Movie
struct Movie: Codable {
    let page: Int?
    let results: [MovieResult]?
    let totalPages, totalResults: Int?

    enum CodingKeys: String, CodingKey {
        case page, results
        case totalPages = "total_pages"
        case totalResults = "total_results"
    }
}

// MARK: - MovieResult
struct MovieResult: Codable  {
    let adult: Bool?
    let backdropPath: String?
    let genreIDS: [Int]?
    let id: Int?
    let originalLanguage, originalTitle, overview: String?
    let popularity: Double?
    let posterPath, releaseDate, title: String?
    let video: Bool?
    let voteAverage: Double?
    let voteCount: Int?
    let character, creditID: String?
    let order: Int?
    let department, job: String?
    
    // 添加CodingKeys映射蛇形字段
    enum CodingKeys: String, CodingKey {
        case adult
        case backdropPath = "backdrop_path"
        case genreIDS = "genre_ids"
        case id
        case originalLanguage = "original_language"
        case originalTitle = "original_title"
        case overview, popularity
        case posterPath = "poster_path"
        case releaseDate = "release_date"
        case title, video
        case voteAverage = "vote_average"
        case voteCount = "vote_count"
        case character
        case creditID = "credit_id"
        case order, department, job
    }
}

3. 调整回调设置顺序 #

在HomeViewController的viewModelConfiguration方法中，你先调用了viewModel.getCatagoryItems()，再设置回调。如果网络请求完成速度快于回调设置，会导致successCallBack和errorCallBack无法触发，无法更新UI或打印错误信息。

修改后的viewModelConfiguration：

fileprivate func viewModelConfiguration(){
    // 先设置回调，再发起请求
    viewModel.errorCallBack = { [weak self] errorMesage in
        print("error: \(errorMesage)")
    }
    viewModel.successCallBack = { [weak self] in
        self?.collectionView.reloadData()
    }
    viewModel.getCatagoryItems()
}

额外优化建议 #

• 在NetworkManager的handleResponse方法中打印解码错误，便于排查：

  fileprivate func handleResponse<T: Codable>(data: Data,completion: @escaping((Result<T, ErrorTypes>)->())){
      do{
          let result = try JSONDecoder().decode(T.self, from: data)
          completion(.success(result))
      }
      catch{
          print("解码错误: \(error)") // 添加错误打印
          completion(.failure(.invalidData))
      }
  }
  

• 优化HomeEndpoint的path实现，避免重复调用HomeEndpoint.popular.rawValue：

  enum HomeEndpoint: String {
      case popular = "movie/popular"
      
      var path: String {
          return NetworkHelper.shared.requestUrl(url: self.rawValue)
      }
  }
  

完成以上修改后，你应该能正常获取TMDB的热门电影数据，cellForItemAt中的print语句也会输出影片的originalTitle。

内容的提问来源于stack exchange，提问作者Mert