I am downloading a bitmap using NSURLConnection. I set the delegate to self, and implement the methods connection:didReceiveData and connectionDidFinishLoading. When data is received, I store it in an NSMutableData object (called input), and then at the end of the connection, I use this to create the bitmap. The problem is that I receive the data in connection:didReceiveData but it is null in connection:DidFinishLoading. How do I fix this?
- (void)start
{
NSURL *url = [NSURL URLWithString:src];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
connection = [[NSURLConnection alloc] initWithRequest:request
delegate:self
startImmediately:YES];
}
- (void)connection:(NSURLConnection *)conn
didReceiveData:(NSData *)d
{
NSLog(#"Data Received: %#", d);//This prints the correct data
//Add data chunk to input
[input appendData:d];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)conn
{
CPLog(#"Finished Receiving bitmap from server. Data received with length %d: %#", [input length], input);//this prints length 0 and a value of (null)
CFDataRef imgData = (__bridge CFDataRef) input;
CGDataProviderRef imgDataProvider = CGDataProviderCreateWithCFData (imgData);
CGImageRef image;
if (!imgDataProvider)
{
NSLog(#"Request Failed!");//happens every time
[callback handleBitmap:nil];
return;
}
image = CGImageCreateWithJPEGDataProvider(imgDataProvider, NULL, true, kCGRenderingIntentDefault);
[callback handleBitmap:image];
return;
}
You should allocate memory for input property. Usually it is done before starting new url connection:
- (void)start
{
self.input = [NSMutableData data];
// .... init and start url connection
}
Related
I have a question about NSURLConnection:
I want download an image with:
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:urlRequest delegate:self];
the first delegate called (correctly) is
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
after this is called one time:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
and immediately:
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
up to here everything is correct, but after connectionDidFinishLoading is fired once again the didReceiveData delegate for the same connection, I identify connection by:
NSString * connectionKey = [[[connection originalRequest] URL] absoluteString];
Is this possible?
update, more infos:
My app fire many simultaneous connections and I store infos for any connection in a dictionary, when a delegate was called I retrive connection info using the key: NSString * connectionKey = [[[connection originalRequest] URL] absoluteString]; for 99% of connections everything is all right but for one (avery time the same!) connection I have this behavior
here the complete implementation:
- (void)downloadFileFromUrl:(NSURL *)url
inPath:(NSString *)completeFilePath
dataReceivedBlock:(void (^)(long long byteDownloaded ,long long totalByte))dataReceivedBlock
endBlock:(void (^)(NSString * downloadPath, NSDictionary * responseHeaders))endBlock
failBlock:(void (^)(NSString * downloadPath, NSDictionary * responseHeaders, NSError * error))failBlock
{
//save the connection infos
NSMutableDictionary * requestData = [[NSMutableDictionary alloc] init];
if(dataReceivedBlock)
[requestData setObject:[dataReceivedBlock copy] forKey:#"dataReceivedBlock"];
if(endBlock)
[requestData setObject:[endBlock copy] forKey:#"endBlock"];
if(failBlock)
[requestData setObject:[failBlock copy] forKey:#"failBlock"];
[requestData setObject:[NSNumber numberWithBool:YES] forKey:#"usingBlock"];
[requestData setObject: completeFilePath forKey:#"downloadDestinationPath"];
//delete the file if already on fs
if([[NSFileManager defaultManager] fileExistsAtPath: completeFilePath])
[[NSFileManager defaultManager] removeItemAtPath:completeFilePath error:nil];
// Create the request.
NSURLRequest * urlRequest = [NSURLRequest requestWithURL:url cachePolicy:NSURLCacheStorageAllowed timeoutInterval:TIME_OUT];
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:urlRequest delegate:self];
if (!theConnection)
{
// Inform the user that the connection failed.
failBlock(completeFilePath,nil,[NSError errorWithDomain:#"Connection fail" code:0 userInfo:nil]);
}
//add connection infos to the requests dictionary
NSString * connectionKey = [[[theConnection originalRequest] URL] absoluteString];
[self.requests setObject:requestData forKey:connectionKey];
}
here a delegate example:
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSString * connectionKey = [[[connection originalRequest] URL] absoluteString];
NSMutableDictionary * requestData = [self.requests objectForKey:connectionKey];
NSFileHandle *file = [requestData objectForKey:#"fileHandle"];
[file closeFile];
//se la richiesta usa o no block
BOOL usingBlock = [[requestData objectForKey:#"usingBlock"] boolValue];
if(usingBlock)
{
__block void (^endBlock)(NSString * , NSDictionary *) = [requestData objectForKey:#"endBlock"];
if(endBlock)
endBlock([requestData objectForKey:#"downloadDestinationPath"],[requestData objectForKey:#"responseHeaders"]);
}
else
[self.delegate downloadEnded:[requestData objectForKey:#"responseHeaders"]];
//elimino dati richiesta
[self.requests removeObjectForKey:[NSString stringWithFormat:#"%#",connectionKey]];
//Inibisco standby
[UIApplication sharedApplication].idleTimerDisabled = NO;
}
It's impossible. It's must be different connection callback.
ensure each connection use unique delegate, or unique switch branch in the same delegate.
Obviously the solution is really simple -_-
The error is in the connection key identifier:
NSString * connectionKey = [[[connection originalRequest] URL] absoluteString];
my assumption is that key are unique, but if I make x parallel downloadS for the same file at the same url the assumption is wrong ;)
I am facing weired issue. I am sending Asynchronus NSUrlrequest call but in return i am getting multiple time responde with some part of json
can someone please help me with what I did wrong.
code
NSString *_query = #"http://abc.com/index.php";
NSData *myRequestData = [NSData dataWithBytes:[_requestString UTF8String]
length:[_requestString length]];
__block NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:_query]];
[request setHTTPMethod: #"POST" ];
[request setValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"content-type"];
[request setHTTPBody: myRequestData ];
[[NSURLConnection alloc] initWithRequest:request delegate:self];
NSRunLoop *runLoop = [NSRunLoop currentRunLoop];
[runLoop addTimer:timeOutTimer forMode:NSDefaultRunLoopMode];
Response
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// check is response is a valid JSON?
NSError *error;
id jsonObj = [NSJSONSerialization JSONObjectWithData: data options:kNilOptions error:&error];
BOOL isValid = [NSJSONSerialization isValidJSONObject:jsonObj];
NSString *content = [[NSString alloc] initWithData:data
encoding:NSUTF8StringEncoding];
NSLog(#"Content: %#",content);
if (isValid)
{
NSDictionary *data = [content JSONValue];
}
[content release];
}
As data is received by the client, this callback gets called:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
didReceiveData is giving you data as it's receiving it and can be called multiple times with chunks of the data.
From the NSURLConnection docs:
The delegate is periodically sent connection:didReceiveData: messages
as the data is received. The delegate implementation is responsible
for storing the newly received data.
From those docs:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// Append the new data to receivedData.
// receivedData is an instance variable declared elsewhere.
[receivedData appendData:data];
}
When its all done, connectionDidFinishLoading will get called and your appended data is ready for you to use.
Finally, if the connection succeeds in downloading the request, the
delegate receives the connectionDidFinishLoading: message. The
delegate will receive no further messages for the connection and the
NSURLConnection object can be released.
I am calling NSURLConnection asynchronous method calls in my view controller. I would like to handle TWO RESPONSES FOR TWO REQUEST in the same Delegate. Please suggest me what would the best approach to achieve this? I'm developing in iOS 5 SDK.
UPDATED:
// Class A
[serverconns setDelegate:self];
connection = [serverconns executeAsyncHttpPost :firstjsonrequest];
[serverconns setDelegate:self];
connection = [serverconns executeAsyncHttpPost :secondjsonrequest];
- (void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
}
- (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
[self.appendData appendData:data];
}
- (void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
// logs the error
}
- (void) connectionDidFinishLoading:(NSURLConnection *)connection
{
NSData *responseData = [[NSData alloc] initWithData:appendData];
//HOW CAN WE HANDLE TWO RESPONSES FOR TWO REQUEST in the same Delegate
if (responseData)
{
// doing something
}
}
//Class B: ServerConnection
- (NSURLConnection *) executeAsyncHttpPost :(id) jsonParams
{
NSString *urlstr = [NSString stringWithFormat:#"%#", baseURL];
urlstr = [urlstr stringByAppendingFormat:method];
NSURL *pUrl = [NSURL URLWithString:urlstr];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:pUrl];
NSData *requestData = [NSData dataWithBytes:[jsonParams UTF8String] length:[jsonParams length]];
[request setHTTPMethod:#"POST"];
[request setValue:#"application/json" forHTTPHeaderField:#"Accept"];
[request setValue:#"application/json" forHTTPHeaderField:#"Content-type"];
[request setHTTPBody: requestData];
return [[NSURLConnection alloc] initWithRequest:request delegate:delegateResponder startImmediately:YES];
}
-(void) setDelegate:(id)newDelegate
{
delegateResponder = newDelegate;
}
save your connections somewhere (maybe ivar of your delegate)
- (void) connectionDidFinishLoading:(NSURLConnection *)connection
{
NSData *responseData = [[NSData alloc] initWithData:appendData];
//HOW CAN WE HANDLE TWO RESPONSES FOR TWO REQUEST in the same Delegate
if (responseData)
{
if (connection == yourFirstConnection) {
// doing something for first connection
} else {
// doing something for second connection
}
}
}
just point out some minor problem of your code
NSString *urlstr = [NSString stringWithFormat:#"%#", baseURL];
urlstr = [urlstr stringByAppendingFormat:method];
should replace to
NSString *urlstr = [baseURL absoluteString];
urlstr = [urlstr stringByAppendingString:method];
and add two(or more or array) weak/assign property of NSURLConnection to your class A (connection delegate)
#property (assign) NSURLConnection *myFirstConnection;
#property (assign) NSURLConnection *mySecondConnection;
// assume only need to handle two connection otherwise NSArray should be used instead
than in your class B (create connection)
- (NSURLConnection *) executeAsyncHttpPost :(id) jsonParams
{
NSString *urlstr = [baseURL absoluteString];
urlstr = [urlstr stringByAppendingString:method];
NSURL *pUrl = [NSURL URLWithString:urlstr];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:pUrl];
NSData *requestData = [NSData dataWithBytes:[jsonParams UTF8String] length:[jsonParams length]];
[request setHTTPMethod:#"POST"];
[request setValue:#"application/json" forHTTPHeaderField:#"Accept"];
[request setValue:#"application/json" forHTTPHeaderField:#"Content-type"];
[request setHTTPBody: requestData];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:delegateResponder startImmediately:YES];
delegateResponder.myFirstConnection = connection;
// delegateResponder.mSecondConnection = connection;
return connection;
}
If I were you I would create a CustomClass which inherits the NSURLConnection. And I will add property called tag.
When I initiate the CustomClass, I would set the tag property and use that to determine which request is being worked on
CustomURLConnection *connection = [[CustomURLConnection alloc] initWithRequest:request delegate:self tag:1];
- (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate tag:(int)_tag
{
if(self = [super initWithRequest:request delegate:delegate])
{
self.tag = _tag;
}
Now in the code you posted add this
- (void) connectionDidFinishLoading:(NSURLConnection *)connection
{
NSData *responseData = [[NSData alloc] initWithData:appendData];
//HOW CAN WE HANDLE TWO RESPONSES FOR TWO REQUEST in the same Delegate
if (responseData)
{
if (connection.tag == 1){
}
}
}
return self;
}
I think all the mentioned solutions are "ugly". I would not implement a solution with delegate methods but instead create a blocks-based solution. I could post an example if you're interested. I would make use of the AFNetworking classes for this approach.
What follows is an example of a class that handles 2 different responses without using a delegate implementation, opting for blocks instead with the AFNetworking library.
- (void)JSONFromService
{
// create the first request and set the methods that handle the return values (either NSData or NSError in this case) in blocks ...
NSURL *firstURL = [NSURL URLWithString:#"http://dl.dropbox.com/u/6487838/test1.html"];
NSURLRequest *firstRequest = [NSURLRequest requestWithURL:firstURL];
AFHTTPRequestOperation *firstOperation = [[AFHTTPRequestOperation alloc] initWithRequest:firstRequest];
[firstOperation setCompletionBlockWithSuccess:^ (AFHTTPRequestOperation *operation, id object)
{
NSString *firstString = [[NSString alloc] initWithData:object encoding:NSASCIIStringEncoding];
NSLog(#"%#", firstString);
} failure:^ (AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"%#", error);
}];
[firstOperation start];
// create the second request and set the methods that handle the return values (either NSData or NSError in this case) in blocks ...
NSURL *secondURL = [NSURL URLWithString:#"http://dl.dropbox.com/u/6487838/test2.html"];
NSURLRequest *secondRequest = [NSURLRequest requestWithURL:secondURL];
AFHTTPRequestOperation *secondOperation = [[AFHTTPRequestOperation alloc] initWithRequest:secondRequest];
[secondOperation setCompletionBlockWithSuccess:^ (AFHTTPRequestOperation *operation, id object) {
NSString *secondString = [[NSString alloc] initWithData:object encoding:NSASCIIStringEncoding];
NSLog(#"%#", secondString);
} failure:^ (AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"%#", error);
}];
[secondOperation start];
}
I usually subclass NSURLConnection and add properties to store whatever context I need to handle the response.
Since the delegate methods get NSURLConnection passed in, you can just cast it back to your subclass and access the context.
Take a look at this example.
I think you should keep all of your connections in an activeConnections array. Every time one finishes, you do [activeConnections indexForObject:connection] and you update your delegate method accordingly, using the index.
Now, a cleaner way to do it( and a better way from my point of view, but this depends on how large is the data you want to transfer) is to use queues. I'll provide a small example and add comments to it:
// we assume you have 2 requests: req1, req2
//now, create a new dispatch queue
dispatch_queue_t netQueue = dispatch_queue_create("com.mycompany.netqueue",DISPATCH_QUEUE_SERIAL);
//execute the operations in the queue ASYNC
//is very important to dispatch this ASYNC on a background thread, otherwise your UI will be stuck until the request finishes
dispatch_async(netQueue,
^{
// We are on a background thread, so we won't block UI events (or, generally, the main run loop)
NSHTTPURLResponse *response = nil;
NSError *error = nil;
NSData *data = nil;
//We can call the request synchronous and block this thread until completed
data = [NSURLConnection sendSynchronousRequest:req1
returningResponse:&response
error:&error];
dispatch_async(dispatch_get_main_queue(),
^{
//call your delegate with the appropriate method for req1
//be sure to copy the contents in data, as we will reuse it with the next request
});
//We can call the other request synchronous and block this thread until completed
data = [NSURLConnection sendSynchronousRequest:req2
returningResponse:&response
error:&error];
dispatch_async(dispatch_get_main_queue(),
^{
//call your delegate with the appropriate method for req2
});
//and this can go on forever. If you have many requests to execute, simply put them in a loop
});
dispatch_release(netQueue);
I was previously downloading images for my app by using dataWithContentsOfURL to download a jpg then writeToFile to save it.
I recent;y started using an NSURLConnetion to do the same, but now I am getting the follwoing errors and a crash:
Corrupt JPEG data: 87 extraneous bytes
JPEG datastream contains no image
I know these images are not corrumpt, as the app was downloading them fine using the previous method. Here is my code:
-(void) downloadSave {
NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];
NSString *tempString = [[NSString alloc]initWithFormat:#"http://www.mysite.com/%#.jpg",chartFileName];
NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:tempString]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:10.0];
// 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.
mutableData = [[NSMutableData data] retain];
self.image = nil;
NSLog(#"connection exists");
[NSURLConnection connectionWithRequest:theRequest delegate:self];
} else {
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:#"Connection Error" message:#"There was an error contacting the chart servers. Please try again." delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alert show];
[alert release];
[activityIndicator stopAnimating];
}
// NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
// NSUserDomainMask, YES);
// NSString *docsPath = [paths objectAtIndex:0];
// NSString *downloadPath = [[[NSString alloc]initWithFormat:#"http://www.mysite.com/%#.jpg",chartFileName]autorelease];
// downloadedChartData = nil;
[pool drain];
[pool release];
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
// This method is called when the server has determined that it
// has enough information to create the NSURLResponse.
// It can be called multiple times, for example in the case of a
// redirect, so each time we reset the data.
// receivedData is an instance variable declared elsewhere.
NSLog(#"got to connection did receive response");
[mutableData setLength:0];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// Append the new data to receivedData.
// receivedData is an instance variable declared elsewhere.
[mutableData appendData:data];
// NSLog(#"got some data, total: %i",mutableData.length);
}
- (void)connection:(NSURLConnection *)connection
didFailWithError:(NSError *)error
{
// release the connection, and the data object
// [connection release];
// receivedData is declared as a method instance elsewhere
// self.mutableData = nil;
// inform the user
//NSLog(#"Connection failed! Error - %# %#",
// [error localizedDescription],
// [[error userInfo] objectForKey:NSErrorFailingURLStringKey]);
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
// do something with the data
// receivedData is declared as a method instance elsewhere
NSLog(#"Succeeded! Received %d bytes of data",[mutableData length]);
[connection release];
// release the connection, and the data object
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
NSString *docsPath = [paths objectAtIndex:0];
self.image = nil;
NSString *savePath = [[[NSString alloc]initWithFormat:#"%#/%#.jpg",docsPath, chartFileName]autorelease];
[mutableData writeToFile:savePath atomically:YES];
self.mutableData = nil;
You are initializing and starting two NSURLConnections with the same delegate. As your delegate methods do not check which connection called them you are mixing up the bytes of two times your image in one NSMutableData instance.
// Creates, initializes and starts an instance of NSURLConnection
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
...
// Creates, initializes and starts another instance of NSURLConnection, with same request and delegate
[NSURLConnection connectionWithRequest:theRequest delegate:self];
Both connections message the same implementations on the same delegate instance, which means their data is written into the same NSMutableData in random order.
I would suggest to simply get rid of the line:
[NSURLConnection connectionWithRequest:theRequest delegate:self];
Another thing: why are you using an autorelease pool in downloadSave? If you call it from the main Thread you have only one NSURLRequest autoreleased in that pool. If you call it from an other Thread you have to take care, that the runloop of that thread is setup and running, or you wouldn't receive any delegate callbacks at all.
I am new to iphone development.I have posted the URL with the user-name and password. I am able to print the data in "connection didReceiveData " method.But i see "connection didReceiveData" method called twice.I don't know ,where i am going wrong. Here is my code
- (void)viewDidLoad {
[super viewDidLoad];
NSString *post = [NSString stringWithFormat:#"&domain=school.edu&userType=2&referrer=http://apps.school.edu/navigator/index.jsp&username=%#&password=%#",#"xxxxxxx",#"xxxxxx"];
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:#"%d",[postData length]];
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
[request setURL:[NSURL URLWithString:[NSString stringWithFormat:#"https://secure.school.edu/login/process.do"]]];
[request setHTTPMethod:#"POST"];
[request setValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"Current-Type"];
[request setHTTPBody:postData];
NSURLConnection *conn = [[NSURLConnection alloc]initWithRequest:request delegate:self];
if(conn)
{
NSLog(#"Connection Successful");
}
else
{
NSLog(#"Connection could not be made");
}
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData*)data{
NSString *string = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSLog(#"the data %#",string);
}
The whole HTML page is printed twice in the console.So please help me out.Thanks.
You may receive the response data in chunks, which is why NSURLConnection's documentation states:
"The delegate should concatenate the contents of each data object delivered to build up the complete data for a URL load."
Use an instance of NSMutableData for this and only process the complete data once you receive the -connectionDidFinishLoading: message.
As MacOS Developer Library states, connection:didReceiveData can be called multiple times if data is received in chunks. That means you have to save all the chunks in some variable and do data processing in connectionDidFinishLoading method. e.g.
NSMutableData *receivedData = [[NSMutableData alloc] init];
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// Append the new data to receivedData.
[receivedData appendData:data];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
// do something with the data, for example log:
NSLog(#"data: %#", [[NSString alloc] initWithData:receivedData encoding:NSUTF8StringEncoding]
}