I'm trying to figure out how to make MKNetworkKit working with data from stream. I can see that some data is beeing downloaded (the indicator on status bar), but I don't have any idea what happens with that data after it's actually downloaded. I put a NSLog statement inside body of connection: didReceiveData: but it's not called during streaming. Any pointers how to fix that issue ?
Edit
Sorry my question was inaccurate. I know how to stream to a file but I need to stream to memory (NSData instance preferably). Okay it seems simple again due to NSOutputStream method initWithBytes:capacity:. And my problem is here, my stream has undefined length so there would be enormous impact on memory. I don't know what to do. My perfect solution works like this. Small chunks of data from the stream are processed having been downloaded and then they are discarded.
You could use the outputStreamToBuffer:capacity: method to create the stream.
As for the buffer, you can use a circular buffer, so that you can read from it as the stream writes to it. A great implementation (and explanation) is here.
Streaming a file download is a three line magic with MKNetworkKit.
//Create a MKNetworkOperation for the remote URL.
MKNetworkOperation *op = [self operationWithURLString:remoteURL
params:nil
httpMethod:#"GET"];
// add your output stream, in this case a file
[op addDownloadStream:[NSOutputStream outputStreamToFileAtPath:filePath
append:YES]];
// enqueue the operation to a MKNetworkEngine.
[self enqueueOperation:op];
That's it.
Related
I am trying to download files from remote, and I now can monitor every single files download success status
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
But any way to monitor the whole process of downloading? How should I know all downloads are finished?
And I tried start download request with
[afhttpClient enqueueBatchOfHTTPRequestOperations:operationArray
progressBlock:progressBlock
completionBlock:completionBlock];
seems not work, so what the difference between above code and start download request with [operation start] in a loop?
#mattt (if you can see this)
You most probably have an NSArray of URL objects that you use to download images. What you need to do is to create an integer value equal to the count of your URL objects. Each time you successfully download an image or absolutely fail to download it (for instance after few timeouts or upon receiving 404 HTTP status code) you need to decrement that integer (note that it should be an atomic property, since blocks are being executed on different threads). Once the count reaches zero - all requests are finished. You can also use that integer to update a progress bar or simply notify user that "#/15 images are downloaded". Let me know if you need any other clarifications.
And unfortunately I have not worked with AFHTTPClient, so I can't tell you the difference between the two operations precisely, but contextually, first one executes all the requests almost at the same time asynchronously and the latter one uses consecutive approach, where second request will only be launched upon completion of the first one.
You can create NSOperationQueue and put all AFHTTPRequestOperation into it.
To observe the "operations" by using KVO. When the count go to zero, that is the time to say all operations completed.
If what you want is a constant progress update for each operation with bytes downloaded and total expected then I can highly recommend Peter Steinberger's AFDownloadRequestOperation.
This class derives from AFHTTPRequestOperation and adds a progressiveDownloadProgressBlock per-operation rather than just a per-operation-completion progress at the operation queue level, which is what I think you're looking for. Another great bonus is that it makes resumable/partial downloads much more accessible than in the core AFNetworking implementation.
it's this easy to use (example from the GitHub project's README.md):
[pdfRequest setProgressiveDownloadProgressBlock:^(NSInteger bytesRead,
long long totalBytesRead, long long totalBytesExpected,
long long totalBytesReadForFile, long long totalBytesExpectedToReadForFile)
{
self.downloadProgress = totalBytesReadForFile/(float)totalBytesExpectedToReadForFile;
}];
I use this in a few enterprise iOS projects to download multi-gigabyte files and I can tell you that it works great with the 1.0.1 release of AFNetworking.
Hope that helps…
I want to read one text file and perform some action on that data.
file size is 67 mb
how can i read.
file is in text format.
its working in simulateor but giving memory warning in device and crashes.
code is
NSString *content = [[[NSString alloc] initWithContentsOfFile:fileName usedEncoding:nil error:nil] autorelease];
crashes when this sentence complete.
Thanks,
Shyam parmar
You haven't given code, but if you are using stringWithContentsOfFile to get an entire file consider using NSInputStream or stdio to read it and process or display it more incrementally.
Fasttracks, try what Peter suggested. The problem is loading it all at once, since you have about 20 MB available for your own app, i believe. If you'd use a NSInputStream, you can load it in pieces, due to which you wont fill up the entire memory at once. Also read this answer to another question: Objective-C: Reading a file line by line
Do you start reading the file from - (void) viewDidLoad? That might be the problem. Try start reading it in a different thread, like: [self performSelectorInBackground:#selector(method) withObject:nil];
Hey fellows,
Iam trying to build an application for realtime voicechanging.
In a first step I managed to record audiodata to a specified file and to play it after recording.
Now I try to change the code for playing back the audiobuffers right after recording them in loop.
My question is, how it is possible to read the Audiodata directly from the recording Audioqueue and not (like shown in documentation) from a file.
Iam thankful for any ideas and could show code-parts if needed.
Thanks in advance,
Lukas (from Germany)
Have a look at the SpeakHere example. This line sources the audio data:
OSStatus result = AudioFileReadPackets(THIS->GetAudioFileID(), false, &numBytes, inCompleteAQBuffer->mPacketDescriptions, THIS->GetCurrentPacket(), &nPackets,
inCompleteAQBuffer->mAudioData);
So, rather than call AudioFileReadPackets, you can just use a memcpy to copy over the recorded data buffer. Or, alternatively, supply to the playback AudioQueue a pointer to the audio data buffer. As playback continues, advance a mCurrentPacket pointer through the buffer.
To record, you'll do something very similar. Rather than writing out to a file, you'll write out to a buffer in memory. You'll first need to allocate that with a malloc. Then are your incoming AudioQueue captures recorded data, you copy that data to the buffer. As more data is copied, you advance the recording head, or mCurrentPacket to a new position.
I have created a java server, which takes screenshots, resizes them, and sends them over TCP/IP to my iPhone application. The application then uses NSInputStream to collect the incoming image data, create an NSMutableData instance with the byte buffer, and then create a UIImage object to display on the iPhone. Screenshare, essentially. My iPhone code to collect the image data is currently as follow:
- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent{
if(streamEvent == NSStreamEventHasBytesAvailable && [iStream hasBytesAvailable]){
uint8_t buffer[1024];
while([iStream hasBytesAvailable]){
NSLog(#"New Data");
int len = [iStream read:buffer maxLength:sizeof(buffer)];
[imgdata appendBytes:buffer length:len];
fullen=fullen+len;
/*Here is where the problem lies. What should be in this
if statement in order to make it test the last byte of
the incoming buffer, to tell if it is the End of Image marker
for the end of incoming JPEG file?
*/
if(buffer[len]=='FFD9'){
UIImage *img = [[UIImage alloc] initWithData:imgdata];
NSLog(#"NUMBER OF BYTES: %u", len);
image.image = img;
}
}
}
}
My problem, as indicated by the in-code comment, is figuring out when to stop collecting data in the NSMutableData object, and use the data to create a UIImage. It seems to make sense to look for the JPEG End of File marker--End of Image (EOI) marker (FFD9)--in the incoming bytes, as the image will be ready for display when this is sent. How can I test for this? I'm either missing something about how the data is stored, or about the marker within the JPEG file, but any help in testing for this would be greatly appreciated!
James
You obviously don't want to close the stream because that would kill performance.
Since you control the client server connection, send down the # of bytes in the image before sending the image data. Better yet, send down # of bytes in the image, the image data, and an easily identified serial # at the end so you can quickly verify that the data has actually arrived.
Much easier and more efficient than actually checking for the end of file marker. Though, of course, you could also just check for that after the # of bytes have been received, too. Easy enough.
Of course, all of this is going to be grossly inefficient for screensharing style purposes in all but the unusual cases. In most cases, only a small part of the screen to be mirrored actually changes with each frame. If you try to send the whole screen with every frame, you'll quickly saturate your connection and the client side will be horribly laggy and unresponsive.
Given that this is an extremely mature market, there are tons of solutions and quite a few open source bits from which you can derive a solution to fit your needs (see VNC, for example).
I am trying to create class that will handle multiple downloads at same time (I need to download a lot of small files) and I have problems with "disappearing" connections.
I have function addDonwload that adds url to list of urls to download, and checks if there is free download slot available. If there is one it starts download immediately. When one of downloads finishes, I pick first url form list and start new download.
I use NSURLConnection for downloading, here is some code
- (bool) TryDownload:(downloadInfo*)info
{
int index;
#synchronized(_asyncConnection)
{
index = [_asyncConnection indexOfObject:nullObject];
if(index != NSNotFound)
{
NSLog(#"downloading %# at index %i", info.url, index);
activeInfo[index] = info;
NSURLRequest *request = [NSURLRequest requestWithURL:info.url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:15];
[_asyncConnection replaceObjectAtIndex:index withObject:[[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:TRUE]];
//[[_asyncConnection objectAtIndex:i] scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
return true;
}
}
return false;
}
- (void)connectionDidFinishLoading:(NSURLConnection*)connection
{
[self performSelectorOnMainThread:#selector(DownloadFinished:) withObject:connection waitUntilDone:false];
}
- (void)DownloadFinished:(id)connection
{
NSInteger index = NSNotFound;
#synchronized(_asyncConnection)
{
index = [_asyncConnection indexOfObject:(NSURLConnection*)connection];
}
[(id)activeInfo[index].delegate performSelectorInBackground:#selector(backgroundDownloadSucceededWithData:) withObject:_data[index]];
[_data[index] release];
[activeInfo[index].delegate release];
#synchronized(_asyncConnection)
{
[[_asyncConnection objectAtIndex:index] release];
[_asyncConnection replaceObjectAtIndex:index withObject:nullObject];
}
#synchronized(downloadQueue)
{
[downloadQueue removeObject:activeInfo[index]];
[self NextDownload];
}
}
- (void)NextDownload
{
NSLog(#"files remaining: %i", downloadQueue.count);
if(downloadQueue.count > 0)
{
if([self TryDownload:[downloadQueue objectAtIndex:0]])
{
[downloadQueue removeObjectAtIndex:0];
}
}
}
_asyncConnection is my array of download slots (NSURLConnections)
downloadQueue is list of urls to download
What happens is, at the beginning everything works ok, but after few downloads my connections start to disappear. Download starts but connection:didReceiveResponse: never gets called. There is one thing in output console that I don't understand I that might help a bit. Normaly there is something like
2010-01-24 21:44:17.504 appName[3057:207]
before my NSLog messages. I guess that number in square brackets is some kind of app:thread id? everything works ok while there is same number, but after some time, "NSLog(#"downloading %# at index %i", info.url, index);" messages starts having different that second number. And when that happens, I stop receiving any callbacks for that urlconnection.
This has been driving me nuts as I have strict deadlines and I can't find problem. I don't have many experiences with iphone dev and multithreaded apps. I have been trying different approaches so my code is kinda messy, but I hope you will see what I am trying to do here :)
btw is anyone of you know about existing class/lib I could use that would be helpful as well. I want parallel downloads with ability o dynamically add new files to download (so initializing downloader at the beginning with all urls is not helpful for me)
You've got a bunch of serious memory issues, and thread synchronization issues in this code.
Rather than go into them all, I'll ask the following question: You are doing this on a background thread of some kind? Why? IIRC NSURLConnection already does it's downloads on a background thread and calls your delegate on the thread that the NSURLConnection was created upon (e.g., your main thread ideally).
Suggest you step back, re-read NSURLConnection documentation and then remove your background threading code and all the complexity you've injected into this unnecessarily.
Further Suggestion: Instead of trying to maintain parallel positioning in two arrays (and some sketchy code in the above relating to that), make one array and have an object that contains both the NSURLConnection AND the object representing the result. Then you can just release the connection instance var when the connection is done. And the parent object (and thus the data) when you are done with the data.
I recommend that you take a look at this:
http://allseeing-i.com/ASIHTTPRequest/
It's a pretty sophisticated set of classes with liberal licensing terms (free too).
It may provide a lot of the functionality that you are wanting.
This snippet can be the source of the bug, you release the object pointed to by the activeInfo[index].delegate pointer right after issuing async method call on that object.
[(id)activeInfo[index].delegate performSelectorInBackground:#selector(backgroundDownloadSucceededWithData:) withObject:_data[index]];
[_data[index] release];
[activeInfo[index].delegate release];
Do you use connection:didFailWithError: ? There may be a timeout that prevents the successful download completion.
Try to get rid of the #synchronized blocks and see what happens.
The string inside the square brackets seems to be thread identifier as you guessed. So maybe you get locked in the #synchronized. Actually, I don't see a reason for switching thread - all the problematic code should run in the main thread (performSelectorOnMainThread)...
Anyhow, there is no need to use both the #synchronized and the performSelectorOnMainThread.
BTW, I didn't see the NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self]; line. Where do you initiate the connection?
As for the parallel downloads - I think that you can download more than one file in a time with the same code that you use here. Just create a separate connection for each download.
Consider just keeping a download queue along with a count of active connections, popping items off the top of the queue when downloads complete and a slot becomes free. You can then fire off NSURLConnection objects asynchronously and process events on the main thread.
If you find that your parallel approach prohibits doing all of the processing on the main thread, consider having intermediary manager objects between your main thread download code and NSURLConnection. Using that approach, you'd instantiate your manager and get it to use NSURLConnection synchronously on a background thread. That manager then completely deals with the downloading and passes the result back to its main thread delegate using a performSelectorOnMainThread:withObject: call. Each download is then just a case of creating a new manager object when you've a slot free and setting it going.