如何使用 Alamofire 在 Swift 5（iOS 应用程序）中获取 http 请求的结果？

Question

I'm trying to get the resilt of an http request (a JSON file) from the following code:

public func performRequest(parameters: [String, String]) -> Any{
    var headers = HTTPHeaders(parameters)
    headers.add(name: "Content-Type", value: "application/x-www-form-urlencoded; charset=UTF-8")
    
    var any : Any?
    
    AF.request(urlEndPointApp, method: .post, parameters: parameters, encoding: URLEncoding.httpBody,  headers: headers).validate().responseJSON{ response in
        switch response.result {
        case .success(let JSON): // stores the json file in JSON variable
            // the JSON file is printed correctly
            print("Validation Successful with response JSON \(JSON)")
            // this variable is seen as nil outside this function (even in return)
            any = JSON
        case .failure(let error):
        print("Request failed with error \(error)")
        }
    }
    
    return any
}

The problem is that, when I print the JSON file from the print("Validation Successful with response JSON \\(JSON)") function, it gets printed correclty. I even tried to print the variable any inside of the block using print("Validation Successful with response JSON \\(any)") and it works, but when it gets returned, its value is nil .

Answer 1

You are using an asynchronous method, so it means you get the result after some time.

You should change your method to

public func performRequest(parameters: [String, String], completion: @escaping (Result<Any, Error>) -> Void) {
    var headers = HTTPHeaders(parameters)
    headers.add(name: "Content-Type", value: "application/x-www-form-urlencoded; charset=UTF-8")
    
    AF.request(urlEndPointApp, method: .post, parameters: parameters, encoding: URLEncoding.httpBody,  headers: headers).validate().responseJSON{ response in
        switch response.result {
        case .success(let JSON): // stores the json file in JSON variable
            // the JSON file is printed correctly
            print("Validation Successful with response JSON \(JSON)")
            // this variable is seen as nil outside this function (even in return)
            completion(.success(JSON))
        case .failure(let error):
            print("Request failed with error \(error)")
            completion(.failure(error))
        }
    }
}