iOS, NSURLSession, NSURLConnection depracated

*** NSURLConnection -> NSURLSession
https://qiita.com/akitaika_/items/2f4fca20a82cb6895329



*** NSURLResponse.expectedContentLength == -1

[request setValue:@"identity" forHTTPHeaderField:@"Accept-Encoding"];

https://stackoverflow.com/questions/23834151/nsurlconnection-expectedcontentlength-returns-1


*** NSURLConnection sendSynchronousRequest

NSURLSession *session = [NSURLSession sharedSession];
[[session dataTaskWithURL:[NSURL URLWithString:londonWeatherUrl]
          completionHandler:^(NSData *data,
                              NSURLResponse *response,
                              NSError *error) {
            // handle response

  }] resume];

https://stackoverflow.com/questions/32643207/ios9-sendsynchronousrequest-deprecated


*** NSURLConnection(procedure method) -> NSURLSession (Blocked method)  
https://tennmemo.blogspot.com/2018/11/objc-method-wait-block-finish.html