Question

I am new to iPhone,

I am currently developing an iPhone app and in which i have implement the ability to download file from the url. I have created the UIWebView, when users clicks on download link in the webview, download will start and i am saving that file to a specified folder in the documents directory, this all things are working fine in my Second View..

but after this when i press a back button for navigating to a my First view, my app gets crashed… shows EXC_BAD_ACCESS

-(void)viewWillAppear:(BOOL)animated{
        //Doing some operation and it works fine...
           NSLog(@"viewWillAppear in First View.......");
    }

-(void)viewDidAppear:(BOOL)animated{
    NSLog(@"viewDidAppear in First View.......");
}

I am able to see above Log When i hit back button but my app crashes after 1 or half second.

Here is my code in Second View,

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    [receivedData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data1
{
    [receivedData appendData:data1];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"Succeeded! Received %d bytes of data",[receivedData length]);

    DirPath=[self applicationDocumentsDirectory];

     NSLog(@"DirPath=%@",DirPath);
    [receivedData writeToFile:DirPath atomically:YES];

    UIAlertView* Alert = [[UIAlertView alloc] initWithTitle:@"Download Complete !"
                                                         message:nil delegate:nil 
                                               cancelButtonTitle:@"OK"
                                               otherButtonTitles:nil];
    [Alert show];
    [Alert release];


    // release the connection, and the data object
    [connection release];
    [receivedData release];
}


- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error1
{
    [connection release];
    [receivedData release];

    // inform the user
    NSLog(@"Connection failed! Error - %@ %@",
          [error1 localizedDescription],
          [[error1 userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
}

- (BOOL)webView:(UIWebView*)webView shouldStartLoadWithRequest:(NSURLRequest*)request navigationType:(UIWebViewNavigationType)navigationType {

    url = [request URL];

    //CAPTURE USER LINK-CLICK.

            DirPath=[self applicationDocumentsDirectory];

            Durl=[[url absoluteString]copy];

            //Checking for Duplicate .FILE at downloaded path....

            BOOL success =[[NSFileManager defaultManager] fileExistsAtPath:path];
            lastPath=[[url lastPathComponent] copy];

            if (success) //if duplicate file found...
            {
                UIAlertView* Alert = [[UIAlertView alloc] initWithTitle:@"This FILE is already present in Library."
                                                                     message:@"Do you want to Downlaod again ?" delegate:self 
                                                           cancelButtonTitle:nil
                                                           otherButtonTitles:@"Yes",@"No",nil];
                [Alert show];
                [Alert release];

            }
            else  //if duplicate file not found directly start download...
            {
                // Create the request.
                NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:Durl]
                                                          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 = [[NSMutableData data] retain];
                } else {
                    NSLog(@"Inform the user that the connection failed."); 
                }

    return YES;   
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{ 
    if (buttonIndex == 0) 
    {        
        // Create the request.
        NSURLRequest *theRequest1=[NSURLRequest requestWithURL:[NSURL URLWithString:Durl]
                                                  cachePolicy:NSURLRequestUseProtocolCachePolicy
                                              timeoutInterval:60.0];

        // create the connection with the request and start loading the data
        NSURLConnection *theConnection1=[[NSURLConnection alloc] initWithRequest:theRequest1 delegate:self];
        if (theConnection1) {
            // Create the NSMutableData to hold the received data.
            receivedData = [[NSMutableData data] retain];
        } else {
            NSLog(@"Inform the user that the connection failed."); 
        }

    }
    else
    {[alertView dismissWithClickedButtonIndex:1 animated:TRUE];}
}

- (void)webView:(UIWebView *)webview didFailLoadWithError:(NSError *)error1 {

    NSLog(@"didFailLoadWithError: %@; stillLoading:%@", error1,(webview.loading?@"NO":@"YES"));
}

My Log shows: didFailLoadWithError: Error Domain=WebKitErrorDomain Code=102 "Frame load interrupted" UserInfo=0x6b34910 {NSErrorFailingURLKey=MY_URL, NSErrorFailingURLStringKey=MY_URL, NSLocalizedDescription=Frame load interrupted}; stillLoading:YES

DirPath=/Users/krunal/Library/Application Support/iPhone Simulator/5.0/Applications/FCDDDE83-A9B3-4C14-A56C-E8C5FCE7F5C4/Documents/DownloadedFile.epub

Any help will be appriciated.

Answer 1

I think your are releasing wrong things… Consider this,

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error1

no need to release connection, receivedData

at dealloc block, add this code

- (void) dealloc
  {
      if (theConnection)
      { 
           [theConnection release], theConnection = nil;
      }

      if (receivedData)
      { 
           [receivedData release], receivedData = nil;
      }
  }

add if you are using same webView to create multiple connection, then add

if (theConnection)
{ 
      [theConnection release], theConnection = nil;
}

if (receivedData)
{ 
     receivedData release], receivedData = nil;
}

before allocating URLConnection and NsMutableData, thats a measure to stop memory leaks. And better to have a activity spinner until event is done.