ios NSURLSession JSON迅速解析为零（在obj-c中可以）

Question

my obj-c code is fine. can someone help me figure out what's wrong with my swift code?

NSURLSession *session = [NSURLSession sharedSession];
[[session dataTaskWithURL:[NSURL URLWithString:url]
        completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
            // handle response
            if (error) {
                TGLog(@"FAILED");
            } else {
                NSError* jsonerror;
                NSDictionary* json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&jsonerror];
                if (jsonerror != nil) {
                    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
                    TGLog(@"response status code: %ld", (long)[httpResponse statusCode]);
                    TGLog(@"%@", jsonerror);
                    return;
                }
                TGLog(@"%@", json);
                TGLog(@"status %@ reason %@", [json objectForKey:@"status"], [json objectForKey:@"reason"]);
            }
        }] resume];

and outputs

2016-11-19 ...._block_invoke:39 status success reason updated

but when I implement it in swift status and reason are nil

var request = URLRequest(url: url)
request.httpMethod = "POST"

URLSession.shared.dataTask(with: request) {data, response, err in
    print("Entered user update completionHandler")

    DispatchQueue.main.async() {
        UIApplication.shared.isNetworkActivityIndicatorVisible = false
    }
    if let error = err as? NSError {
        print(error.localizedDescription)
    } else if let httpResponse = response as? HTTPURLResponse {
        if httpResponse.statusCode == 200 {
            do {
                let json = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as! [String: Any]
                print(json)
                let status = json["status"] as? [String:Any]
                let reason = json["reason"] as? [String:Any]
                // TODO: this is always printing out nil values - haven't figure out the swift problem yet
                print("status \(status) reason \(reason)")
            } catch let error as NSError {
                    print(error)
            }
        }
    }

}.resume()

my webpage outputs

{"status":"success","reason":"updated","uuid":"blahblahblahbahaldsh"}

Answer 1

Read the JSON, status and reason are String rather than a dictionary

 let status = json["status"] as? String
 let reason = json["reason"] as? String

According to the given JSON you could even cast json to [String:String]

let json = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as! [String:String]

then you get rid of the other type casts

 let status = json["status"]
 let reason = json["reason"]

The result of both lines is optional String . As you seem to be responsible for the web service you can unwrap the optionals if your service sends always the keys status and reason

 let status = json["status"]!
 let reason = json["reason"]!