类型 'MovieSearchContainer.Type' 不能符合 'Decodable';只有 struct/enum/class 类型可以符合协议
Type 'MovieSearchContainer.Type' cannot conform to 'Decodable'; only struct/enum/class types can conform to protocols
我写了一个泛型函数,但是在使用这个函数时出现错误。这个错误的原因是什么?我将 Codable 添加到我的模型中。我找不到这个问题的原因。
错误
Type 'MovieSearchContainer.Type' cannot conform to 'Decodable'; only struct/enum/class types can conform to protocols
型号
struct MovieSearchContainer: Codable {
var page: Int
var results: [MovieSearch]
}
struct MovieSearch: Codable {
var id: Int
var title: String
}
电影服务
class MovieBaseService {
func fetchNewspaper<T: Codable>(stringUrl: String, model: T, completion: @escaping (T) -> ()) {
if let url = URL(string:stringUrl) {
let session = URLSession(configuration: .default)
var request = URLRequest(url: url)
request.httpMethod = "GET"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
let task = session.dataTask(with: request as URLRequest) { (data, response, error) in
if error == nil {
let decoder = JSONDecoder()
if let movieData = data {
do {
let results = try decoder.decode(T.self, from: movieData)
completion(results)
} catch {
print(error)
}
}
}
}
task.resume()
}
}
}
SearchMovieVM
class SearchMovieVM: ObservableObject {
var searchMovieService = MovieBaseService()
@Published var searchedMovie: [MovieSearch] = []
@Published var query: String = ""
@Published var page: Int = 1
func getSearchingMovie() {
self.searchMovieService.fetchNewspaper(stringUrl: "https://api.themoviedb.org/3/search/movie?api_key=594b8eb4999a8b44ad5136ee3ed1ebdb&language=tr-TR&query=\(query)&page=1&include_adult=false", model: MovieSearchContainer) { (result) in
}
}
}
在您的案例中,编译器可以使用完成闭包推断泛型 T
func fetchNewspaper<T: Codable>(stringUrl: String, completion: @escaping (T) -> ())
service.fetchNewspaper(stringUrl: url) { (result: MovieSearchContainer) in
// ...
}
除非您想明确传递模型类型,在这种情况下
func fetchNewspaper<T: Codable>(stringUrl: String, model: T.Type, completion: @escaping (T) -> ())
service.fetchNewspaper(stringUrl: url, model: MovieSearchContainer.self) { result in
// ...
}
有关 Swift 泛型的更多信息,请参阅 official docs
我写了一个泛型函数,但是在使用这个函数时出现错误。这个错误的原因是什么?我将 Codable 添加到我的模型中。我找不到这个问题的原因。
错误
Type 'MovieSearchContainer.Type' cannot conform to 'Decodable'; only struct/enum/class types can conform to protocols
型号
struct MovieSearchContainer: Codable {
var page: Int
var results: [MovieSearch]
}
struct MovieSearch: Codable {
var id: Int
var title: String
}
电影服务
class MovieBaseService {
func fetchNewspaper<T: Codable>(stringUrl: String, model: T, completion: @escaping (T) -> ()) {
if let url = URL(string:stringUrl) {
let session = URLSession(configuration: .default)
var request = URLRequest(url: url)
request.httpMethod = "GET"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
let task = session.dataTask(with: request as URLRequest) { (data, response, error) in
if error == nil {
let decoder = JSONDecoder()
if let movieData = data {
do {
let results = try decoder.decode(T.self, from: movieData)
completion(results)
} catch {
print(error)
}
}
}
}
task.resume()
}
}
}
SearchMovieVM
class SearchMovieVM: ObservableObject {
var searchMovieService = MovieBaseService()
@Published var searchedMovie: [MovieSearch] = []
@Published var query: String = ""
@Published var page: Int = 1
func getSearchingMovie() {
self.searchMovieService.fetchNewspaper(stringUrl: "https://api.themoviedb.org/3/search/movie?api_key=594b8eb4999a8b44ad5136ee3ed1ebdb&language=tr-TR&query=\(query)&page=1&include_adult=false", model: MovieSearchContainer) { (result) in
}
}
}
在您的案例中,编译器可以使用完成闭包推断泛型 T
func fetchNewspaper<T: Codable>(stringUrl: String, completion: @escaping (T) -> ())
service.fetchNewspaper(stringUrl: url) { (result: MovieSearchContainer) in
// ...
}
除非您想明确传递模型类型,在这种情况下
func fetchNewspaper<T: Codable>(stringUrl: String, model: T.Type, completion: @escaping (T) -> ())
service.fetchNewspaper(stringUrl: url, model: MovieSearchContainer.self) { result in
// ...
}
有关 Swift 泛型的更多信息,请参阅 official docs