将映像上传到服务器IOS7后，应用程序崩溃

嗨，我正在将图像从设备上传到服务器，但是在将图像上传到服务器后却崩溃了。在代码中，我给出了类似的规定，例如在上传图像后，必须在添加此代码后返回主视图，使其不断崩溃。

上载验证码

    NSString *urlString = @"http://indianpoliticalleadersmap.com/IOS/upload/photos/upload.php";

    NSData *imageData = UIImageJPEGRepresentation(imageview.image,90);
    long imageSize = imageData.length;
    NSLog(@"SIZE OF IMAGE: %.2f Mb", (float)imageSize/1024/1024);
 if (imageSize > 4.194e+6) {

     UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Sorry" message:@"your image exceeds more then 4mb pls upload below 4mb image" delegate:self cancelButtonTitle:@"ok" otherButtonTitles:nil, nil];
     [alert show];
     [alert release];
    }
   else
  {
       NSString *urlString = @"url";

       NSMutableURLRequest *request = [[[NSMutableURLRequest alloc]init]autorelease];
       [request setURL:[NSURL URLWithString:urlString]] ;
       [request setHTTPMethod:@"POST"];

       NSString *boundary = @"---------------------------14737809831466499882746641449";
       NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@",boundary];
       [request addValue:contentType forHTTPHeaderField:@"Content-Type"];

       NSMutableData *body = [NSMutableData data];
       [body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary]dataUsingEncoding:NSUTF8StringEncoding]];
       [body appendData:[@"Content-Disposition: form-data; name=\"userfile\"; filename=\".jpg\"\r\n"dataUsingEncoding:NSUTF8StringEncoding]];
       [body appendData:[@"Content-Type: application/octet-stream\r\n\r\n"dataUsingEncoding:NSUTF8StringEncoding]];
       [body appendData:[NSData dataWithData:imageData]];
       [body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n", boundary]dataUsingEncoding:NSUTF8StringEncoding]];
       [request setHTTPBody:body];

       NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
       NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];

       NSLog(@"%@data",returnString);
       [self temp];
       [self performSelector:@selector(myMethod) withObject:nil afterDelay:3.0f];
       [self performSelector:@selector(dissMissViewController) withObject:self afterDelay:4.0f];
       alertTimer = [NSTimer scheduledTimerWithTimeInterval:2 target:self selector:@selector(showAlert) userInfo:nil repeats:NO];

     }
   }

当我单击警报消息中的“确定”应用程序崩溃时，警报消息弹出后，该应用程序崩溃。请告诉我如何解决此问题。

  -(void)showAlert{

     UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Thanks" message:@"For uploading Image" delegate:self cancelButtonTitle:nil otherButtonTitles:@"ok", nil];
     [alert show];
     [alert release];
    }

谢谢。