I'm quite new to iPhone development. My target is a remote control app, the server of which is TightVNC. But I met a problem and it's driving me crazy... I've successfully connected to the server(using socket), and next would like to request desktop update at least every one second. So here comes the timer which is created through the selector in "performSelectorInBackground". The timer's main task is as fellow:
int picLength;
[self readExact:(char*)(&picLength) bySize:sizeof(int)];
char *picBuffer;
picBuffer = (char *)malloc(picLength);
[self readExact:picBuffer bySize:picLength];
NSData *picData = [[NSData alloc]initWithBytes:picBuffer length:picLength];
[self performSelectorOnMainThread:#selector(setPicInMainThread:) withObject:picData waitUntilDone:YES];
[picData release];
free(picBuffer);
And "setPicInMainThread" is as follow (each picture is around 200KB, iTouch is connected to PC through computer-to-computer wifi, so the speed would be fast enough):
- (void) setPicInMainThread:(NSData *)data {
[chatController.imageView.image release];
chatController.imageView.image = [UIImage imageWithData:data];
}
The app crushes after presenting the first desktop update. I am wondering if I've met the "memory leak" concerning NSTimer and NSData, which lots of people is talking about... If so, is there any way to solve the problem? Thank you very much for helping!
Your malloc code is looking bad. Why would you take the address of an int and then cast it as a character pointer? Then why would even pass an int for the size to the same function you pass a char * to get set? I have a feeling you are getting an EXC_BAD_ACCESS and it is because of your first few lines and the readExact method. Make sure you get the length the correct and pass the correct parameters.
int picLength;
[self readExact:(char*)(&picLength) bySize:sizeof(int)];
char *picBuffer;
picBuffer = (char *)malloc(picLength);
Related
I am capturing frames from the camera using the code:
- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
:(AVCaptureConnection *)connection
{
// Create a UIImage from the sample buffer data
UIImage *image = [self imageFromSampleBuffer:sampleBuffer];
if(delegate && [delegate respondsToSelector:#selector(captureManagerCapturedFrame:withFrameImage:withFrameBuffer:)]) {
[delegate captureManagerCapturedFrame:self withFrameImage:image withFrameBuffer:sampleBuffer];
}
}
I am doing this because in the delegate method captureManagerCapturedFrame:withFrameImage:withFrameBuffer: I have a flag which tells the app to use either the returned uiimage OR the returned sampleBuffer.
The delegate method is:
- (void) captureManagerCapturedFrame:(AVCamCaptureManager *)captureManager
withFrameImage:(UIImage *)image
withFrameBuffer:(CMSampleBufferRef)frameBuffer {
if(_screen1) {
NSLog(#"Only display camera image\n");
}
else if(_screen2) {
//Enable IR
NSLog(#"Display AND Process camera image\n");
[self imageReconigitionProcessFrame:frameBuffer];
}
}
where imageReconigitionProcessFrame: is:
-(void)imageReconigitionProcessFrame:(CMSampleBufferRef)frameBuffer {
//CFRetain(frameBuffer);
MSImage *qry = [[MSImage alloc] initWithBuffer:frameBuffer orientation:AVCaptureVideoOrientationPortrait]; //MEMORY LEAK HERE???
qry = nil;
//CFRelease(frameBuffer);
}
This code effectively works. But here is my problem. When this code is run and profiled in instruments, I see a rapid increase in the overall bytes used, but the allocations profiler doesn't appear to increase. Nor do a see any 'leaks' using the leaks tool. But clearly, there is a rapid memory gain each time imageReconigitionProcessFrame: is called and the app crashes after a few seconds. When I set frameBuffer to nil, there is NO increase in memory (or course I also don't have the frame buffer to do any processing with).
I have tried transfering ownership of frameBuffer using CFRetain and CFRelease (commented out in the above code), but these don't seem to do anything either.
Does anyone have any idea where I could be leaking memory inside this function???
The method [[MSImage alloc] initWithBuffer: is form a third party SDK (Moodstocks, which is an awesome image recognition SDK) and it works just fine in their demos, so I don't think the problem is inside this function.
First of all, thanks for mentioning Moodstocks (I work for them): we're happy that you find our SDK useful!
To answer your question, I guess your code does indeed contain a leak: at the end of the imageReconigitionProcessFrame method, you should call [qry release]. The rule in Obj-C is quite simple: whenever you manually call alloc on an object, it should also be manually released!
That's BTW what is done in the Moodstocks SDK wrapper: if you look at the [MSScannerSession session: didOutputSampleBuffer:] method, you'll see that we do manually release the MSImage object after it's been processed.
As to why the profiler doesn't find this leak, I guess that it's due to the fact that leaks are analyzed every 10 seconds by default: in this case, the memory leak is so heavy (1280x720 frames, at 15+ FPS if you're on an iPhone 5, for 10 seconds: at least 130 MB leaked) that the code must crash before the first 10 seconds are reached.
Hope this helps!
I hope it's even possible.
I've got code to load really big file (dictionary) after app started:
- (void)applicationDidFinishLaunching:(UIApplication *)application {
NSString *filePath = [NSString stringWithContentsOfFile:[[NSBundle mainBundle]
pathForResource:#"en_US" ofType:#"txt"]
encoding:NSUTF8StringEncoding error:nil];
dictionary = [NSSet setWithArray:[NSArray arrayWithArray:
[filePath componentsSeparatedByCharactersInSet:
[NSCharacterSet whitespaceAndNewlineCharacterSet]]]];
}
Also I've got proper code in viewDidLoad:
- (void)viewDidLoad {
[super viewDidLoad];
self.progressView.progress = 0.0;
[self performSelectorOnMainThread:
#selector(applicationDidFinishLaunching:)
withObject:nil
waitUntilDone:NO];
}
But I've got not a clue how to force UIProgressView to show progress of creating NSSet dictionary from an NSArray. It takes few seconds in iOS Simulator, so on device it can take over a dozen. I really need to show progress, and I prefer this way than Activity Indicator View.
I'm interested in how to get count of imported items at the moment (count of all items is known).
Any idea? :)
You need to use NSURLRequest/NSURLConnection to start an asynchronous request to get the dictionary data. The delegates of NSURLConnection will give you the bytes read and bytes remaining where you can perform a async dispatch to the main thread to update your progress view value.
If you have a long text file to parse, the framework classes will take long time. You can't change that. And you can't change that they will never call back during work to tell you about their progress.
Your only chance is to perform text file splitting on your own and set your progress as you dig yourself through your textfile. You can split a textfile with regular expressions. The "\w+" collect words with at least one character.
If you set the progress bar in a heavy working method you have to give it some time to refresh the screen once in a while. See the "futuredate magic" below.
Maybe the following can act as a starting point - in the code below the content of the text file is stored in the NSString "content".
NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression
regularExpressionWithPattern:#"\\w+"
options:NSRegularExpressionCaseInsensitive
error:&error];
[regex enumerateMatchesInString:content
options:0
range:NSMakeRange(0, [content length])
usingBlock:^(NSTextCheckingResult *match, NSMatchingFlags flags, BOOL *stop){
// push one match to the dictionary
[dictionary addObject:[content substringWithRange:match.range]];
// update the progress bar
NSDate* futureDate = [NSDate dateWithTimeInterval:0.001 sinceDate:[NSDate date]];
[[NSRunLoop currentRunLoop] runUntilDate:futureDate];
self.progressbar.progress = (float) match.range.location/content.length;
}];
Note that the code is not optimized for speed. For example you should not update the progress bar with every token. Depending on how much tokens you have - count the detected ones and update the pgogress bar every 100 matches, or so...
Use SVProgressHUD. It has delegates such as showProgress to show progress.
EDIT:
Note that this is just a suggestion to the approach and not practical implementation. Depending on your observation you may or may not choose to implement it.
If it's a local file, you can take some calculated guess about the total time it takes to read the entire file. Then divide this time by 100.
Create an async queue to read from file using one of arrayWithContentsOfFile or dictionaryWithContentsOfFile or whatever. Implement a timer on main thread, and increment progress by 1 through it, and keep posting progress on main thread (do not read progress from async thread because it is never going to tell you of that, we are faking it).
Once arrayWithContentsOfFile returns, post 100% on main thread. You may need to tweak a bit to be accurate (like in Windows where you keep seeing file download time fluctuating) but variation will not be much I suppose. Every type of target device would have given hardware and memory so it would be simply a function of file size.
I have four urls which consists images...
I'm downloding those images and placing them into documents folder..
here is my code..
-(void)viewDidLoad
{
NSMutableArray *myUrlsArray=[[NSMutableArray alloc]init];
[myUrlsArray addObject:#"http://blogs.sfweekly.com/thesnitch/steve_jobs3.jpg"];
[myUrlsArray addObject:#"http://www.droid-life.com/wp-content/uploads/2012/12/Steve-Jobs-Apple.jpg"];
[myUrlsArray addObject:#"http://2.bp.blogspot.com/-T6nbl0rQoME/To0X5FccuCI/AAAAAAAAEZQ/ipUU7JfEzTs/s1600/steve-jobs-in-time-magazine-front-cover.png"];
[myUrlsArray addObject:#"http://images.businessweek.com/ss/08/09/0929_most_influential/image/steve_jobs.jpg"];
[myUrlsArray addObject:#"http://cdn.ndtv.com/tech/gadget/image/steve-jobs-face.jpg"];
for (int i=0; i<myUrlsArray.count; i++)
{
[self downloadImageFromURL:[myUrlsArray objectAtIndex:i] withName:[NSString stringWithFormat:#"MyImage%i.jpeg",i]];
}
}
#pragma mark- downloading File
-(void)downloadImageFromURL:(NSString *)myURLString withName:(NSString *)fileName
{
UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:myURLString]]];
NSLog(#"%f,%f",image.size.width,image.size.height);
// Let's save the file into Document folder.**
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES) objectAtIndex:0];
NSString *jpegPath = [NSString stringWithFormat:#"%#/%#",documentsPath,fileName];// this path if you want save reference path in sqlite
NSData *data2 = [NSData dataWithData:UIImageJPEGRepresentation(image, 1.0f)];//1.0f = 100% quality
[data2 writeToFile:jpegPath atomically:YES];
}
NOW... I need to display a UIProgressView for above downloading progress accurately.
how can i achieve this functionality...
Can any one provide some guidelines to achieve this..
Thanks in advance...
I'd suggest you use some asynchronous downloading technique (either AFNetworking, SDWebImage, or roll your own with delegate-based NSURLSession) rather than dataWithContentsOfURL so that (a) you don't block the main queue; and (b) you can get progress updates as the downloads proceed.
I'd also suggest creating a NSProgress for each download. When your delegate method gets updates about how many bytes have been downloaded, update the NSProgress object.
You then can associate each NSProgress with a observedProgress for a UIProgressView, and when you update your NSProgress, the UI can be updated automatically.
Or, if you and a single UIProgressView to show the aggregate progress of all of the NSProgress for each download, you can create a parent NSProgress, establish each download's NSProgress as a child of the parent NSProgress, and then, as each download updates its respective NSProgress, this will automatically trigger the calculation of the parent NSProgress. And again, you can tie that parent NSProgress to a master UIProgressView, and you'll automatically update the UI with the total progress, just by having each download update its individual NSProgress.
There is a trick, though, insofar as some web services will not inform you of the number of bytes to be expected. They'll report an "expected number of bytes" of NSURLResponseUnknownLength, i.e. -1! (There are logical reasons why it does that which are probably beyond the scope of this question.) That obviously makes it hard to calculate what percentage has been downloaded.
In that case, there are a few approaches:
You can throw up your hands and just use an indeterminate progress indicator;
You can try changing the request such that web service will report meaningful "expected number of bytes" values (e.g. https://stackoverflow.com/a/22352294/1271826); or
You can use an "estimated download size" to estimate the percentage completion. For example, if you know your images are, on average, 100kb each, you can do something like the following to update the NSProgress associated with a particular download:
if (totalBytesExpectedToWrite >= totalBytesWritten) {
self.progress.totalUnitCount = totalBytesExpectedToWrite;
} else {
if (totalBytesWritten <= 0) {
self.progress.totalUnitCount = kDefaultImageSize;
} else {
double written = (double)totalBytesWritten;
double percent = tanh(written / (double)kDefaultImageSize);
self.progress.totalUnitCount = written / percent;
}
}
self.progress.completedUnitCount = totalBytesWritten;
This is a bit of sleight of hand that uses the tanh function to return a "percent complete" value that smoothly and asymptotically approaches 100%, using the kDefaultImageSize as the basis for the estimation.
It's not perfect, but it yields a pretty decent proxy for percent completion.
Your call to dataWithContentsOfURL is synchronous, meaning you don't get updates as the download is in process.
You can use a library like AFNetworking (https://github.com/AFNetworking/AFNetworking) which has callbacks to the progress of the download.
Actually a better solution is to use SDWebImage manager which will load the images in the background for you and cache them. Then the next time you use that image it will check the cache. Google it.
That way the user also doesn't have to sit around and wait while you're downloading stuff..
Then look at this other question that has some ideas on how to do a status:
How to show an activity indicator in SDWebImage
Do not use dataWithContentsOfURL, you are blocking the main thread until the data arrives.
Instead create your own connection with NSURLConnection and start listening to your delegate.
connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response: get the total data size with [response expectedContentLength].
connection:(NSURLConnection *)connection didReceiveData:(NSData *)data: This is where you do your calculations and update your UIProgressView. Something like, loadedBytes/total data size.
Good luck.
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.
I am building a game that pulls images randomly. After doing some testing I have realized if the same image is called twice, it crashes. I learned this by after completing the first game, I returned to the games main menu and selected to play again. I ended up getting an image which was already displayed to me in my previous game and a second later my app crashed. I did some testing and made the same image show up twice during my first game, and it crashed a second after the image was displayed a second time.
Here is a sample code. "idNum" and "timer" are declared in the .h file so they are global. As you can see I have NSTimer that runs every second to randomize a new image to be pulled. Works find until an image is trying to be shown for a second time. Say I get a random order of 1,3,2,5,3. It will crash on the second 3.
Can you not call an image twice? I can only think that this is a caching issue, I am not sure how to release the image cache. I get the error objc_msgSend. Sorry not very good at debugging crashes.
//idNum = the randomly generated integer
//pictures are called by numbers ex(1.jpg, 5.jpg)
timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(timeCounter) userInfo:nil repeats:YES];
-(void)timeCounter {
time = time + 1;
idNum = (arc4random() % 5);
NSString * imgIDnum = [[NSString alloc] initWithFormat:#"%d", idNum];
imgMain = [NSString stringWithFormat:#"%#%#", imgIDnum, #".jpg"];
[imgIDnum release];
UIImage * daImg = [UIImage imageNamed:imgMain];
[imgView setImage:daImg];
}
You should provide more information about the crash. Is it in the +imageNamed: line above, or perhaps in -setImage:?
The most likely cause is that you are over-releasing the UIImage. For instance, if you're calling [daImg release] after the above code, then you would get this behavior because you would be over-releasing something that the UIImage class is caching. This wouldn't cause a crash until the situation you describe.
I've seen a really entertaining version of this bug: a teammate of mine was over-releasing an NSNumber (it happened to be for the integer 2 most of the time). NSNumbers are cached internally, so the next time he created an NSNumber for the integer 2, in an unrelated part of the program, it would crash. Any other number was fine, but try to NSLog() a 2, and boom.
Well I am sorry to say that I have fixed the issue and have no idea how. I ended up re-writing majority of that code, adding, removing and changing some snippets around to be more memory management friendly. When I went to run it again things were perfectly fine. Sorry for no solution. If someone else comes across this problem, let me know I will try and help.