未將對象引用設置爲對象的實例在XML中

Question

我是iPhone新手，在我的應用程序中使用XML，我需要將一個圖像發送到服務器的一個特定文件夾。出於同樣的我使用的代碼：

NSString *filename = @"Image"; 
NSData *imageData = UIImageJPEGRepresentation([imageView image], 90); 
NSString *urlString = [NSString stringWithFormat:@"http://111.111.11.1/webservices.asmx/PutImage"]; 

//網址是：http://111.111.11.1/webservices.asmx/PutImage?ImgIn=image.jpg

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

NSString *boundary = [NSString stringWithString:@"--------1473780983"]; 
NSString *contentType = [NSString stringWithFormat:@"application/x-www-form-urlencoded;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:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"images\"; filename=\"%@.jpg\"\r\n", filename] dataUsingEncoding:NSUTF8StringEncoding]]; 
[body appendData:[[NSString stringWithString:@"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(@"\n\n\nreturnString : %@",returnString); 

我得到的消息，如：在返回字符串「未設置爲一個對象的實例對象引用」 。任何人都可以指導我解決一些問題嗎？

Answer 1

好吧......我嘗試使用的代碼，即時通訊....

// ImageView的是一個UIImageView

NSData *imageData = UIImageJPEGRepresentation(imageview.image, 100); 


// setting up the URL to post to 
NSString *urlString = @"http://example.com/upload"; 

// setting up the request object now 

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

/* 
add some header info now 
we always need a boundary when we post a file 
also we need to set the content type 

You might want to generate a random boundary.. this is just the same 
as my output from wireshark on a valid html post 
*/ 
NSString *boundary = [NSString stringWithString:@"---------------------------14737809831466499882746641449"]; 
NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@",boundary]; 
[request addValue:contentType forHTTPHeaderField: @"Content-Type"]; 

/* 
now lets create the body of the post 
*/ 

NSMutableData *body = [NSMutableData data]; 
[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];  
[body appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"userfile\"; filename=\".jpg\"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; 
[body appendData:[[NSString stringWithString:@"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]]; 
// setting the body of the post to the reqeust 
[request setHTTPBody:body]; 

// now lets make the connection to the web 

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

Answer 2

從iPhone上傳數據到服務器：

- (void)sendImage { 

       NSData *postData = [nsdata from your original image]; 
       NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]]; 

       // Init and set fields of the URLRequest 
       NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init]; 
       [request setHTTPMethod:@"POST"]; 
       [request setURL:[NSURL URLWithString:[NSString stringWithString:@"http://yoururl.domain"]]]; 

       [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"]; 
       [request setValue:postLength forHTTPHeaderField:@"Content-Length"]; 
       [request setHTTPBody:postData]; 

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

       if (connection) { 
        // Return data of the request 
         NSData *receivedData = [[NSMutableData data] retain]; 
       } 
      [request release]; 

     }