I have a video decoder playing H264 using AVSampleBufferDisplayLayer and all works well until I scroll a UICollectionViewController on the same View Controller. This appears to block the main thread causing the app to crash. I have tried putting this code in a block on a separate queue using dispatch_async but still have the same blocking problem along with further performance issues on the decoder.
dispatch_async(sampleQueue, ^{
[sampleBufferQueue addObject:(__bridge id)(sampleBuffer)];
if ([avLayer isReadyForMoreMediaData]) {
CMSampleBufferRef buffer = (__bridge CMSampleBufferRef)([sampleBufferQueue objectAtIndex:0]);
[sampleBufferQueue removeObjectAtIndex:0];
[avLayer enqueueSampleBuffer:buffer];
buffer = NULL;
NSLog(#"I Frame");
[avLayer setNeedsDisplay];
while ([sampleBufferQueue count] > 0 && [avLayer isReadyForMoreMediaData]) {
CMSampleBufferRef buffer = (__bridge CMSampleBufferRef)([sampleBufferQueue objectAtIndex:0]);
[sampleBufferQueue removeObjectAtIndex:0];
[avLayer enqueueSampleBuffer:buffer];
buffer = NULL;
NSLog(#"I Frame from buffer");
[avLayer setNeedsDisplay];
}
}
else {
NSLog(#"AVlayer Not Accepting Data (I)");
}
});
Is there a way to give this task priority over User Interface actions like scrolling a Collection View etc? Apologies for lack of understanding I am reasonably new to IOS.
Turns out the UICollectionView was blocking the delegate calls for NSURLConnection on the main thread. This solved the problem:
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request
delegate:self];
changed to
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request
delegate:self
startImmediately:NO];
[connection scheduleInRunLoop:[NSRunLoop currentRunLoop]
forMode:NSRunLoopCommonModes];
[connection start];
Related
I'm looking for a means to handle separate but related NSURLRequest and thought that I could add them to an NSOperationQueue and then manage them (run the request or not based on http status code - if the status code is 200 they can run, if not, stop all of them as the url string needs to be appended).
In my test code below I suspend the OQ to stop the processing of NSURLRequest (represented here by some public RSS feeds) but continue to the request to the OQ. I get the right number of operations (4). After adding all request to the OQ I then check to see if it has been suspended and if so, cancel all the operations.That works, at least the check if it has been suspended.
When I do a count check after canceling the operations I still get 4 but was expecting less (and hoping for 0). I'm using NSURLConnection to get the rss data in a NSObject subclass.
I understand from the docs that NSOQ will not remove an operation until it has reported that it is finished. (Is there a way to see this report?)
You cannot directly remove an operation from a queue after it has been added. An operation remains in its queue until it reports that it is finished with its task. Finishing its task does not necessarily mean that the operation performed that task to completion. An operation can also be canceled. Canceling an operation object leaves the object in the queue but notifies the object that it should abort its task as quickly as possible.
NSURLConnection doesn't have a willStart or similar delegate method so I can't track that but my feeling is the second RSS feed is in some sort of start process and that would explain why it is still in there. But I log the connectionDidFinishLoading delegate and so the first task is completed, so I was expecting at least that to be gone.
So my question is twofold.
1. If I nil out NSOQ, does that eliminate the operations within it? And what danger is there if one of those operations is in process - crash, hanging the app, etc?
2. Is there a way to cancel a NSURLConnection that is in process? (Assuming that the answer to 1 is yes, you are in the danger zone).
Here's my code:
- (void)viewDidLoad {
[super viewDidLoad];
connectionManager* myConnectionManager = [[connectionManager alloc] init];
NSOperationQueue* operationQueue = [[NSOperationQueue alloc] init];
NSMutableArray* arrAddedOperations = [[NSMutableArray alloc] init];
NSArray* arrFeeds = [[NSArray alloc] initWithObjects:#"http://rss.cnn.com/rss/cnn_topstories.rss", #"http://hosted.ap.org/lineups/USHEADS-rss_2.0.xml?SITE=RANDOM&SECTION=HOME", #"http://feeds.reuters.com/reuters/topNews", #"http://newsrss.bbc.co.uk/rss/newsonline_world_edition/americas/rss.xml", nil];
//add operations to operation queue
for(int i=0; i<arrFeeds.count; i++) {
NSInvocationOperation* rssOperation = [[NSInvocationOperation alloc]
initWithTarget: myConnectionManager
selector:#selector(runConnection:)
object:[arrFeeds objectAtIndex:i]];
//check to put a suspension on the OQ
if (i>1) {
operationQueue.suspended = YES;
}
[operationQueue addOperation:rssOperation];
[arrAddedOperations addObject:[arrFeeds objectAtIndex:i]];
//incremental count to see operations being added to the queue - should be 4
NSLog(#"This is the number of operations added to the queue:%i", [operationQueue operationCount]);
}
if (operationQueue.suspended) {
//restart the OQ so we can cancel all the operations
operationQueue.suspended = NO;
//kill all the operations
[operationQueue cancelAllOperations];
//count to see how many operations are left
NSLog(#"OQ has been suspended and operations canclled. The operation count should be 0\nThe operation count is %i", [operationQueue operationCount]);
}
}
from NSURLConnection class
- (void) runConnection : (NSString*) strURL {
NSURLRequest* urlRequest = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:strURL]];
self.myConnection = [[NSURLConnection alloc] initWithRequest:urlRequest delegate:self startImmediately:NO];
[self.myConnection setDelegateQueue:self.myQueue];
[self.myConnection start];
self.myConnection = nil;
}
#pragma mark - NSURLConnection Delegates
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
NSLog(#"%#", error.localizedDescription);
}
- (void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
NSHTTPURLResponse* httpResponse = (NSHTTPURLResponse*)response;
NSLog(#"%#", [NSNumber numberWithInteger:httpResponse.statusCode]);
}
- (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
self.strReponse = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
//NSLog(#"%#", self.strReponse);
}
- (void) connectionDidFinishLoading:(NSURLConnection *)connection {
NSLog(#"task finished");
NSDictionary* dictUserInfo = [[NSDictionary alloc] initWithObjectsAndKeys:
#"Display Data", #"Action",
self.strReponse, #"Data",
nil];
[[NSNotificationCenter defaultCenter] postNotificationName:#"avc" object:self userInfo:dictUserInfo];
}
Edit: I don't need to save these operations as I am storing the incoming request in a mutable array and which just create a new OQ once they have been appended. I just want to make sure they are cancelled and not leaving the app in a fragile state.
I have a project that connects to an external accessory and communicates a small amount of data to and from an iOS app. I am able to setup the session and streams like apple does in their EADemo reference code and everything seems to work fine.
The problem I have is that after a random amount of time using the app, the output stream stops working, but the input stream still operates fine. I check to make sure hasSpaceAvailable is true before each write attempt and when I read back the number of bytes written, everything looks correct. Also, looking at the run loop doesn't indicate any differences between working and non working, and the stream status still reads as open.
The only thing that I can see that causes this is that my accessory doesn't ACK a few of the app's write attempts in a row, and then it breaks.
How can I detect I am in this state and how can I fix it?
// low level write method - write data to the accessory while there is space available and data to write
- (void)_writeData {
while (([[_session outputStream] hasSpaceAvailable]) && ([_dataToWrite length] > 0))
{
NSInteger bytesWritten = [[_session outputStream] write:[_dataToWrite bytes] maxLength:[_dataToWrite length]];
if (bytesWritten == -1)
{
NSLog(#"write error");
break;
}
else if (bytesWritten > 0)
{
[_dataToWrite replaceBytesInRange:NSMakeRange(0, bytesWritten) withBytes:NULL length:0];
}
}
}
// low level read method - read data while there is data and space available in the input buffer
- (void)_readData {
NSLog(#"reading data to buffer");
#define EAD_INPUT_BUFFER_SIZE 128
uint8_t buf[EAD_INPUT_BUFFER_SIZE];
while ([[_session inputStream] hasBytesAvailable])
{
NSInteger bytesRead = [[_session inputStream] read:buf maxLength:EAD_INPUT_BUFFER_SIZE];
if (_dataToRead == nil) {
_dataToRead = [[NSMutableData alloc] init];
}
[_dataToRead appendBytes:(void *)buf length:bytesRead];
}
[[NSNotificationCenter defaultCenter] postNotificationName:EASessionDataReceivedNotification object:self userInfo:nil];
}
// high level write data method
- (void)writeData:(NSData *)data
{
// NSLog(#"writing data to buffer");
if (_dataToWrite == nil) {
_dataToWrite = [[NSMutableData alloc] init];
}
[_dataToWrite appendData:data];
[self _writeData];
}
// high level read method
- (NSData *)readData:(NSUInteger)bytesToRead
{
NSLog(#"reading data");
NSData *data = nil;
if ([_dataToRead length] >= bytesToRead) {
NSRange range = NSMakeRange(0, bytesToRead);
data = [_dataToRead subdataWithRange:range];
[_dataToRead replaceBytesInRange:range withBytes:NULL length:0];
}
return data;
}
- (BOOL)openSession
{
NSLog(#"openSession");
[_accessory setDelegate:self];
if(_session){
[self closeSession];
}
_session = [[EASession alloc] initWithAccessory:_accessory forProtocol:_protocolString];
if (_session)
{
_runLoop = [NSRunLoop currentRunLoop];
[[_session inputStream] setDelegate:self];
[[_session inputStream] scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[[_session inputStream] open];
[[_session outputStream] setDelegate:self];
[[_session outputStream] scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[[_session outputStream] open];
NSLog(#"creating session succeeded!");
}
else
{
NSLog(#"creating session failed!");
}
return (_session != nil);
}
I think I may be experiencing the same problem. I have a bluetooth connected accessory, and when I am testing range I often end up in a situation with exactly the same symptoms that you describe in your question.
But how do you detect that the problem is caused by the accessory failing to ACK data?
I am guessing in my situation the Accessory is sending ACK's but the because I am on the edge of bluetooth range my phone never receives the ACK.
Right now my best bet is to try and detect the situation in the APP. In my situation I can do this because the accessory will resend the same package if it does not receive any data from the phone. So if I see the same data transmitted from the accessory a number of times I will drop the connection and ask the user to move closer to the accessory, and reconnect.
Good day, here's what i am trying to do:
i have a photo processing app that takes images using AVFoundation
i have a DeviceMotion queue that is processing device position at 60Hz
when image is taken, it needs to be cropped and saved. DeviceMotion needs to keep running and interface updated without delays
what i am seeing is: updates to interface from DeviceMotion queue are being frozen for the duration of image crop.
this is how i start updates for DeviceMotion:
self.motionManager.deviceMotionUpdateInterval = 1.0f/60.0f;
gyroQueue = [[NSOperationQueue alloc] init];
[self.motionManager startDeviceMotionUpdatesToQueue:gyroQueue withHandler:^(CMDeviceMotion *motion, NSError *error){
[NSThread setThreadPriority:1.0];
[self processMotion:motion withError:error];
}];
when images is returned from AVFoundation it is added to the queue for processing:
imageProcessingQueue = [[NSOperationQueue alloc] init];
[imageProcessingQueue setName:#"ImageProcessingQueue"];
[imageProcessingQueue setMaxConcurrentOperationCount:1];
//[imageProcessingQueue addOperationWithBlock:^{
//[self processImage:[UIImage imageWithData:imageData]];
//}];
NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self selector:#selector(processImage:) object:[UIImage imageWithData:imageData]];
[operation setThreadPriority:0.0];
[operation setQueuePriority:NSOperationQueuePriorityVeryLow];
[imageProcessingQueue addOperation:operation];
and the method for processing the image:
- (void)processImage:(UIImage*)image {
CGSize cropImageSize = CGSizeMake(640,960);
UIImage *croppedImage = [image resizedImageWithContentMode:UIViewContentModeScaleAspectFit bounds:cropImageSize interpolationQuality:kImageCropInterpolationQuality];
NSData *compressedImageData = UIImageJPEGRepresentation(croppedImage, kJpegCompression);
[self.doc addPhoto:compressedImageData];
}
the issue is:
devicemotion updates are blocked for the duration of image crop when image is processed using the NSOperationQueue
if i process the image using performSelectorInBackground - it works as desired (no delays to DeviceMotion queue)
[self performSelectorInBackground:#selector(processImage:) withObject:[UIImage imageWithData:imageData]];
any ideas on where my understanding of background threading needs an update? :)
PS. I have asked this question earlier but it got nowhere, so this is a re-post
i have found a solution (or solid workaround) for this issue:
instead of routing deviceMotion updates to the queue using startDeviceMotionUpdatesToQueue, i have created a CADisplayLink timer and it is not interfering with other background queues - while it is matching screen refresh rate it's given highest priority by it's nature:
[self.motionManager startDeviceMotionUpdates];
gyroTimer = [CADisplayLink displayLinkWithTarget:self selector:#selector(processMotion)];
[gyroTimer addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
I'm trying to pull images from the server for the scrollview. After the user zooms the view in or out, the image should be downloaded:
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale {
Ymin=365000+375000*_scrollView.contentOffset.x/(scale*1024);
Ymax=365000+375000*(_scrollView.contentOffset.x/scale+1024/scale)/1024;
Xmin=6635000-260000*(_scrollView.contentOffset.y/scale+748/scale)/748;
Xmax=6635000-260000*_scrollView.contentOffset.y/(scale*748);
[self looYhendus]; //Creates NSURLConnection and downloads the image according to scale, Ymin, Ymax, Xmin and Xmax values
UIImage *saadudPilt=_kaardiPilt;
imageView=[[UIImageView alloc] initWithImage:saadudPilt];
imageView.frame=CGRectMake(_scrollView.contentOffset.x,_scrollView.contentOffset.y,1024,748);
[_scrollView addSubview:imageView];
}
On some occasions (I can't figure out, on what conditions), it works, but on some occasions NSURLConnection delegate methods won't get fired and the image set as the subview is still the image that is initially downloaded (when the application launches). Then, only after I touch the screen again (the scrollview scrolls), the NSLog message shows that the image is downloaded. What could be the reason of this kind of a behaviour?
EDIT: Added the NSURLConnection delegate methods. I've tried a few other ways but they all end up not executing the delegate methods. Which made me think that it's not about NSURConnection but rather UIScrollView (obviously, I can be wrong about this).
- (void)looYhendus
{
yhendused=CFDictionaryCreateMutable(
kCFAllocatorDefault,
0,
&kCFTypeDictionaryKeyCallBacks,
&kCFTypeDictionaryValueCallBacks);
NSString *aadress = [NSString stringWithFormat:#"http://xgis.maaamet.ee/wms-pub/alus?version=1.1.1&service=WMS&request=GetMap&layers=MA-ALUSKAART&styles=default&srs=EPSG:3301&BBOX=%d,%d,%d,%d&width=%d&height=%d&format=image/png",Ymin,Xmin,Ymax,Xmax,512,374];
NSURL *url = [[NSURL alloc] initWithString:aadress];
NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:url];
NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
if( theConnection )
{
andmedServerist = [NSMutableData data];
CFDictionaryAddValue(
yhendused,
(__bridge void *)theConnection,
(__bridge_retained CFMutableDictionaryRef)[NSMutableDictionary
dictionaryWithObject:[NSMutableData data]
forKey:#"receivedData"]);
}
CFRunLoopRun();
}
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
[andmedServerist setLength: 0];
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
NSMutableDictionary *connectionInfo =
(NSMutableDictionary*)objc_unretainedObject(CFDictionaryGetValue(yhendused, (__bridge void *)connection));
[[connectionInfo objectForKey:#"receivedData"] appendData:data];
}
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Ühenduse viga" message:#"Kõige tõenäolisemalt on kaardiserveril probleeme või puudub seadmel internetiühendus" delegate:self cancelButtonTitle:#"Sulge" otherButtonTitles:nil];
[alert show];
CFRunLoopStop(CFRunLoopGetCurrent());
}
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSMutableDictionary *connectionInfo =
(NSMutableDictionary*)objc_unretainedObject(CFDictionaryGetValue(yhendused, (__bridge void *)connection));
[connectionInfo objectForKey:#"receivedData"];
andmedServerist=[connectionInfo objectForKey:#"receivedData"];
_kaardiPilt = [UIImage imageWithData: andmedServerist];
CFDictionaryRemoveValue(yhendused, (__bridge void *)connection);
CFRunLoopStop(CFRunLoopGetCurrent());
}
EDIT: added this:
- (void)viewDidLoad
{
[super viewDidLoad];
Ymin=365000;
Ymax=740000;
Xmin=6375000;
Xmax=6635000;
[self looYhendus];
UIImage *saadudPilt=_kaardiPilt;
imageView=[[UIImageView alloc] initWithImage:saadudPilt];
imageView.frame=CGRectMake(0,0,1024,748);
[_scrollView addSubview:imageView];
[_scrollView setContentSize: CGSizeMake(1024, 748)];
_scrollView.minimumZoomScale = 1.0;
_scrollView.maximumZoomScale = 50.0;
_scrollView.delegate = self;
}
Why are you explicitly calling CFRunLoopRun(); and stopping it in connectionDidFinishLoading: or didFailWithError: methods ? (CFRunLoopStop(CFRunLoopGetCurrent());)
Assuming you are doing this on main thread. You are stopping mainthread's runloop. There can be timers, ScrollView uses events which stop responding because you stopped the main thread's runloop.
If you are calling NSURLConnection on the main thread you don't need to explicitly run it (or stop it). You can just schedule to run on current runloop which is main threads runloop. If you are doing it on a background thread, then your code seems valid (Although you shouldn't show UIAlertView in didFailWithError: if its called on separate thread).
Updated Answer(Based on #Shiim's comment):
In the viewDidLoad method you are calling [self looYhendus]; which returns immediately (as you are using Asynchronous URL Connection for the load). So its working as expected. Move [scrollView addSubview:imageView] to connectionDidFinishLoading: method which would add your downloaded imageView data to scrollView's subView once finished downloading it. Or you can consider using dispatch_queue's to create a thread and load the URL request synchronously then using dispatch_queue's main queue to dispatch drawing of imageView added as subView to ScrollView onto main thread.
My recommendation in your case would be redesigned approach using dispatch_queue's. Which would be give you better understanding of solving problem (in this scenario) and also improves your code readability.
I had the same problem recently. The issue was that I was putting my connection in an asynchronous thread, when connections are already asynchronous.
I found the solution here: NSURLConnection delegate methods are not called
There are also a few links to other people who had similar issues in that thread.
If I were you though, I would try simply using [theConnection start] and initializing the request with a set timeout so you don't have to worry about the background thread shutting out before the image is downloaded.
For example:
[request setTimeoutInterval:30];
We have a large project that needs to sync large files from a server into a 'Library' in the background. I read subclassing NSOperation is the most flexible way of multithreading iOS tasks, and attempted that. So the function receives a list of URLs to download & save, initialises an instance of the same NSOperation class and adds each to an NSOperation queue (which should download only 1 file at a time).
-(void) LibSyncOperation {
// Initialize download list. Download the homepage of some popular websites
downloadArray = [[NSArray alloc] initWithObjects:#"www.google.com",
#"www.stackoverflow.com",
#"www.reddit.com",
#"www.facebook.com", nil];
operationQueue = [[[NSOperationQueue alloc]init]autorelease];
[operationQueue setMaxConcurrentOperationCount:1]; // Only download 1 file at a time
[operationQueue waitUntilAllOperationsAreFinished];
for (int i = 0; i < [downloadArray count]; i++) {
LibSyncOperation *libSyncOperation = [[[LibSyncOperation alloc] initWithURL:[downloadArray objectAtIndex:i]]autorelease];
[operationQueue addOperation:libSyncOperation];
}
}
Now, those class instances all get created fine, and are all added to the NSOperationQueue and begin executing. BUT the issue is when it's time to start downloading, the first file never begins downloading (using an NSURLConnection with delegate methods). I've used the runLoop trick I saw in another thread which should allow the operation to keep running until the download is finished. The NSURLConnection is established, but it never starts appending data to the NSMutableData object!
#synthesize downloadURL, downloadData, downloadPath;
#synthesize downloadDone, executing, finished;
/* Function to initialize the NSOperation with the URL to download */
- (id)initWithURL:(NSString *)downloadString {
if (![super init]) return nil;
// Construct the URL to be downloaded
downloadURL = [[[NSURL alloc]initWithString:downloadString]autorelease];
downloadData = [[[NSMutableData alloc] init] autorelease];
NSLog(#"downloadURL: %#",[downloadURL path]);
// Create the download path
downloadPath = [NSString stringWithFormat:#"%#.txt",downloadString];
return self;
}
-(void)dealloc {
[super dealloc];
}
-(void)main {
// Create ARC pool instance for this thread.
// NSAutoreleasePool *pool = [[NSAutoreleasePool alloc]init]; //--> COMMENTED OUT, MAY BE PART OF ISSUE
if (![self isCancelled]) {
[self willChangeValueForKey:#"isExecuting"];
executing = YES;
NSURLRequest *downloadRequest = [NSURLRequest requestWithURL:downloadURL];
NSLog(#"%s: downloadRequest: %#",__FUNCTION__,downloadURL);
NSURLConnection *downloadConnection = [[NSURLConnection alloc] initWithRequest:downloadRequest delegate:self startImmediately:NO];
// This block SHOULD keep the NSOperation from releasing before the download has been finished
if (downloadConnection) {
NSLog(#"connection established!");
do {
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
} while (!downloadDone);
} else {
NSLog(#"couldn't establish connection for: %#", downloadURL);
// Cleanup Operation so next one (if any) can run
[self terminateOperation];
}
}
else { // Operation has been cancelled, clean up
[self terminateOperation];
}
// Release the ARC pool to clean out this thread
//[pool release]; //--> COMMENTED OUT, MAY BE PART OF ISSUE
}
#pragma mark -
#pragma mark NSURLConnection Delegate methods
// NSURLConnectionDelegate method: handle the initial connection
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse*)response {
NSLog(#"%s: Received response!", __FUNCTION__);
}
// NSURLConnectionDelegate method: handle data being received during connection
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[downloadData appendData:data];
NSLog(#"downloaded %d bytes", [data length]);
}
// NSURLConnectionDelegate method: What to do once request is completed
-(void)connectionDidFinishLoading:(NSURLConnection *)connection {
NSLog(#"%s: Download finished! File: %#", __FUNCTION__, downloadURL);
NSFileManager *fileManager = [NSFileManager defaultManager];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docDir = [paths objectAtIndex:0];
NSString *targetPath = [docDir stringByAppendingPathComponent:downloadPath];
BOOL isDir;
// If target folder path doesn't exist, create it
if (![fileManager fileExistsAtPath:[targetPath stringByDeletingLastPathComponent] isDirectory:&isDir]) {
NSError *makeDirError = nil;
[fileManager createDirectoryAtPath:[targetPath stringByDeletingLastPathComponent] withIntermediateDirectories:YES attributes:nil error:&makeDirError];
if (makeDirError != nil) {
NSLog(#"MAKE DIR ERROR: %#", [makeDirError description]);
[self terminateOperation];
}
}
NSError *saveError = nil;
//NSLog(#"downloadData: %#",downloadData);
[downloadData writeToFile:targetPath options:NSDataWritingAtomic error:&saveError];
if (saveError != nil) {
NSLog(#"Download save failed! Error: %#", [saveError description]);
[self terminateOperation];
}
else {
NSLog(#"file has been saved!: %#", targetPath);
}
downloadDone = true;
}
// NSURLConnectionDelegate method: Handle the connection failing
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
NSLog(#"%s: File download failed! Error: %#", __FUNCTION__, [error description]);
[self terminateOperation];
}
// Function to clean up the variables and mark Operation as finished
-(void) terminateOperation {
[self willChangeValueForKey:#"isFinished"];
[self willChangeValueForKey:#"isExecuting"];
finished = YES;
executing = NO;
downloadDone = YES;
[self didChangeValueForKey:#"isExecuting"];
[self didChangeValueForKey:#"isFinished"];
}
#pragma mark -
#pragma mark NSOperation state Delegate methods
// NSOperation state methods
- (BOOL)isConcurrent {
return YES;
}
- (BOOL)isExecuting {
return executing;
}
- (BOOL)isFinished {
return finished;
}
NOTE: If that was too unreadable, I set up a QUICK GITHUB PROJECT HERE you can look through. Please note I'm not expecting anyone to do my work for me, simply looking for an answer to my problem!
I suspect it has something to do with retaining/releasing class variables, but I can't be sure of that since I thought instantiating a class would give each instance its own set of class variables. I've tried everything and I can't find the answer, any help/suggestions would be much appreciated!
UPDATE: As per my answer below, I solved this problem a while ago and updated the GitHub project with the working code. Hopefully if you've come here looking for the same thing it helps!
In the interests of good community practice and helping anyone else who might end up here with the same problem, I did end up solving this issue and have updated the GitHub sample project here that now works correctly, even for multiple concurrent NSOperations!
It's best to look through the GitHub code since I made a large amount of changes, but the key fix I had to make to get it working was:
[downloadConnection scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
This is called after the NSURLConnection is initialized, and just before it is started. It attaches the execution of the connection to the current main run loop so that the NSOperation won't prematurely terminate before the download is finished. I'd love to give credit to wherever first posted this clever fix, but it's been so long I've forgotten where, apologies. Hope this helps someone!