从NSURLConnection POST方法获取数据

Question

I have subclassed an NSData object into my .h and .m files like so:

@interface Test : NSData // and so forth

I have created a function that generates JSON data to send back to the server as a POST . I get to this part in the code:

NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:request delegate:self]; 

Question 1:

How do I tell when the connection/post is done? Is it in the if/else below?

if(conn) {
    NSLog(@"Connection Successful");
} else {
    NSLog(@"Connection could not be made");
}

Question 2:

How do I use these delegate methods below to get the data that is returned?

// This method is used to receive the data which we get using post method.
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData*)data

// This method receives the error report in case of connection is not made to server. 
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error 

// This method is used to process the data after connection has made successfully.
- (void)connectionDidFinishLoading:(NSURLConnection *)connection

Answer 1

this worked for me

NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"API link"]

NSLog(@"%@",url.standardizedURL);
NSMutableURLRequest *request=[NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:@"POST"];
[request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
[NSURLConnection sendAsynchronousRequest:request
                                   queue:[NSOperationQueue mainQueue]
                       completionHandler:^(NSURLResponse *response,
                                           NSData *data, NSError *connectionError)
 {
     NSLog(@"balh %@",connectionError);
     if (data.length > 0 && connectionError == nil)
     {
         NSDictionary *response = [NSJSONSerialization JSONObjectWithData:data
                                                                  options:0
                                                                    error:NULL];
         NSString * string = [[NSString alloc] initWithData:data encoding:NSStringEncodingConversionAllowLossy];
         NSLog(@"%@ %@",response,string);



         [self dismissViewControllerAnimated:YES completion:^{

         }];
     }
 }];

for checking connection you can use this statements after NSURLConnection statement

 if(response){NSLog(@"Connection Established");}else{NSLog(@"Connection not established");}

Answer 2

You have to use delegate methods for verification of operation success and to get the data in returned.

- (void)connection:(NSURLConnection *)connection
didReceiveResponse:(NSURLResponse *)response 
{
    NSLog("@Resp received");
    return;
}

- (void)connection:(NSURLConnection *)connection
    didReceiveData:(NSData *)data 
{
    NSLog("@Data received");
    return
}

- (void)connection:(NSURLConnection *)connection
  didFailWithError:(NSError *)error 
{
    NSLog("@ERROR: Achtung !: %@",[error localizedDescription]);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection 
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH , 0),, ^{
        NSLog(@"FinishedLoading: In bg thread, do something with data here");

        dispatch_async( dispatch_get_main_queue(), ^{
            NSLog(@"FinishedLoading: In Main thread, access the UI here");
        });
    });
}

Answer 3

set HTTP method (POST or GET). Write this lines as it is in your code.

[request setHTTPMethod:@"POST"];