Question

I was recently looking at an example from apple about NSURLConnection and I tried implementing it into my code but I am not sure if am I doing it right.

Basically I want the connection to go to my website where I have it connected to a php script that runs the search within my database and then echo’s it to the browser. I want the iphone to take the line that is echoed and hold it into a string variable. This is my code.
Is this correctly done?

Thank you in advance

  NSString *stringToBeSent= [[NSString alloc] initWithFormat:
    @"http:/xxxxx/siteSql.php?  data=%@",theData];

      NSURLRequest *theRequest=[NSURLRequest requestWithURL:
      [NSURL URLWithString:stringToBeSent]
      cachePolicy:NSURLRequestUseProtocolCachePolicy
     timeoutInterval:60.0];


   // create the connection with the request
    // and start loading the data
 NSURLConnection *theConnection=[[NSURLConnection alloc] 
 initWithRequest:theRequest  delegate:self];


   if (theConnection) {
    // Create the NSMutableData to hold the received data.
    // receivedData is an instance variable declared elsewhere... in my .h file
    // NSMutableData *receivedData; 

    receivedData = [[NSMutableData data] retain];

     //convert NSMutableData to a string
    NSString *stringData= [[NSString alloc] 
      initWithData:receivedData encoding:NSUTF8StringEncoding];

    NSLog (@"result%@", receivedData);

    } else {
    // Inform the user that the connection failed.


    NSLog(@"failed");

      }

Answer 1

I think you might be missing a couple things:

1. In the method that you use to trigger retrieving the data make sure you release the old data before initializing:

   [retrievedData release];
   retrievedData=[[NSMutableData alloc] init];
   

2. I assume that space is a typo or something for the URL?

3. You don’t need to call requestWithURL:cachePolicy:timeoutInterval: requestWithURL: uses the same defaults as you chose.

4. The data will come in blocks. You’ve got to handle that over time, outside this method, using the delegate method connection:didReceiveData:, like so:

   - (void)connection:(NSURLConnection *)conn didReceiveData:(NSData *)data
   {
        [receivedData appendData:data];
   }
   

5. Similarly, if you want something done with the data once it’s all received, you do it in connectionDidFinishLoading: NOTE THAT THE CONNECTION IS RELEASED so it has to be defined in your header as an instance variable (eg. NSURLConnection *connection;

   - (void)connectionDidFinishLoading:(NSURLConnection *)conn
   {
      NSString *stringData= [[NSString alloc] 
      initWithData:receivedData encoding:NSUTF8StringEncoding]; 
      NSLog(@"Got data? %@", stringData);
      [connection release];
       connection = nil;
      // Do unbelievably cool stuff here //
   }
   

6. Also look into the other delegate methods like connection:didFailWithError: You probably want to release the connection and stringData there as well, in case of an error.

I hope that’s of some help! Enjoy!