How to catch if any failure happens in Alamofire 4 - ios

Question

I am calling my webservice in this way.
public func prepareUrl (baseUrl: String, appendString: String, bindedParams: String, isAuthorized: Bool, method: HTTPMethod, jsonBody: [String:String], callback: #escaping (String) ->Void> Void)
{
let dm=Datamanager.sharedInstance
let baseUrl=dm.globalUrl
let urlString=baseUrl!+appendString as String+bindedParams as String
print(urlString)
Alamofire.request(urlString, method: method, parameters: nil, encoding: JSONEncoding.default)
.downloadProgress(queue: DispatchQueue.global(qos: .utility)) { progress in
print("Progress: \(progress.fractionCompleted)")
}
.validate { request, response, data in
// Custom evaluation closure now includes data (allows you to parse data to dig out error messages if necessary)
return .success
}
.responseJSON { response in
debugPrint(response)
callback("success")
}
}
But how can I do error handling here. Even If I referred the github Alamofire 4.0 migration I don't have clear idea how to do it.
Please help me.
thanks

Answer 1

In Alamofire gitHub has the method:
You don't need the validate, Alamofire default validation is that 200 to 299 is success, you can get the error from the response.
public func prepareUrl (baseUrl: String, appendString: String, bindedParams: String, isAuthorized: Bool, method: HTTPMethod, jsonBody: [String:String], callback: #escaping (String) ->Void> Void)
{
let dm=Datamanager.sharedInstance
let baseUrl=dm.globalUrl
let urlString=baseUrl!+appendString as String+bindedParams as String
print(urlString)
Alamofire.request(urlString, method: method, parameters: nil, encoding: JSONEncoding.default)
.downloadProgress(queue: DispatchQueue.global(qos: .utility)) { progress in
print("Progress: \(progress.fractionCompleted)")
}
.responseJSON { response in
debugPrint(response)
switch response.result {
case .success:
callback("success")
case .failure(let error):
print(error)
}
}
}
Checkout the documentation