To retrieve the OpenID configuration from the URL "https://localhost:44389/.well-known/openid-configuration" in Objective-C, you can use the NSURLSession class to send an HTTP GET request and retrieve the response. Here's an example code snippet:

NSURL *url = [NSURL URLWithString:@"https://localhost:44389/.well-known/openid-configuration"];
NSURLSessionDataTask task = [[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData data, NSURLResponse response, NSError error) {
    if (error) {
        NSLog(@"Error: %@", error);
    } else {
        // Process the response data
        NSString *responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
        NSLog(@"Response: %@", responseString);
[task resume];

This code creates an NSURL object with the URL string, then uses NSURLSession to create a data task with the URL. The completion handler is called when the task completes, and you can process the response data within the completion handler. In this example, the response data is converted to a string and logged to the console.

Please note that this code assumes you have a valid SSL certificate for the localhost domain. If you're using a self-signed certificate or a certificate from a non-trusted authority, you may need to configure your app to trust the certificate.