I am downloading images from a url using NSDATA and saving them to local file system using
NSData *dataForStorage = [NSData dataWithData:UIImagePNGRepresentation(img)];
BOOL saveResult=[ dataForStorage writeToFile:jpegFilePath options:NSDataWritingAtomic error:&error];
NSLog(#"Write returned error: %#", [error localizedDescription]);
My app crashes randomly without even giving a message, though some files are saved (again randomly). When I run the app in Debug mode, I frequently see "EXC_BAD_ACCESS" but continuing execution succeeds in saving some of the files.
This code is executed in background from:
[self performSelectorInBackground:#selector(loadImageInBackground:) withObject:arr];
Please suggest.
One of the problems in your code is that your running code in a thread without an autorelease pool but are using functions that would require one. Put the following code into the loadImageInBackground method:
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
// existing code
[pool drain];
This is probably just one of several problems. For further assistance, we need to see the stack trace of the crash.
Just a wild guess : arr is an autoreleased object, so, sometimes it gets deallocated before your selector gets called. Try using [arr copy] and release it after saving it.
I was having the EXACT same problem, but it turned out that the problem was something else: my URL was getting release prematurely. In the end this is what I did and it worked:
I made this call:
[self performSelectorInBackground:#selector(downloadData:) withObject:nil];
And this is the method:
// URL - (NSString) URL for file
// filePath - (NSString) save location on device
-(void)download:(NSString *)URL
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:URL]];
[data writeToFile:filePath atomically:YES];
[pool release];
}
So I think that your download code is correct, but there is some other variable that is getting deallocated early (possibly your path).
Hope this helps! I know the other answers on this page worked for me.
Related
I've been trying to make do (see this and this) with the recent NSUserScriptTask class and its subclasses and so far I've solved some problems, but some others remain to be solved. As you can see from the docs, NSUserScriptTask does not allow for the cancellation of tasks. So, I decided to create a simple executable that takes as arguments the path to the script and runs the script. That way, I can launch the helper from my main app using NSTask and call [task terminate] when necessary. However, I require:
The main app to receive output and errors from the helper it launched
The helper only terminating when the NSUserScriptTask is done
The code for the main app is simple: just launch an NSTask with the proper info. Here's what I have now (for the sake of simplicity I ignored the code for security-scoped bookmarks and the like, which are out of the problem. But don't forget this is running sandboxed):
// Create task
task = [NSTask new];
[task setLaunchPath: [[NSBundle mainBundle] pathForResource: #"ScriptHelper" ofType: #""]];
[task setArguments: [NSArray arrayWithObjects: scriptPath, nil]];
// Create error pipe
NSPipe* errorPipe = [NSPipe new];
[task setStandardError: errorPipe];
// Create output pipe
NSPipe* outputPipe = [NSPipe new];
[task setStandardOutput: outputPipe];
// Set termination handler
[task setTerminationHandler: ^(NSTask* task){
// Save output
NSFileHandle* outFile = [outputPipe fileHandleForReading];
NSString* output = [[NSString alloc] initWithData: [outFile readDataToEndOfFile] encoding: NSUTF8StringEncoding];
if ([output length]) {
[output writeToFile: outputPath atomically: NO encoding: NSUTF8StringEncoding error: nil];
}
// Log errors
NSFileHandle* errFile = [errorPipe fileHandleForReading];
NSString* error = [[NSString alloc] initWithData: [errFile readDataToEndOfFile] encoding: NSUTF8StringEncoding];
if ([error length]) {
[error writeToFile: errorPath atomically: NO encoding: NSUTF8StringEncoding error: nil];
}
// Do some other stuff after the script finished running <-- IMPORTANT!
}];
// Start task
[task launch];
Remember, I need the termination handler to only run when: (a) the task was cancelled (b) the task terminated on its own because the script finished running.
Now, on the helper side things start to get hairy, at least for me. Let's imagine for the sake of simplicity that the script is an AppleScript file (so I use the NSUserAppleScriptTask subclass - on the real world I'd have to accomodate for the three types of tasks). Here's what I got so far:
int main(int argc, const char * argv[])
{
#autoreleasepool {
NSString* filePath = [NSString stringWithUTF8String: argv[1]];
__block BOOL done = NO;
NSError* error;
NSUserAppleScriptTask* task = [[NSUserAppleScriptTask alloc] initWithURL: [NSURL fileURLWithPath: filePath] error: &error];
NSLog(#"Task: %#", task); // Prints: "Task: <NSUserAppleScriptTask: 0x1043001f0>" Everything OK
if (error) {
NSLog(#"Error creating task: %#", error); // This is not printed
return 0;
}
NSLog(#"Starting task");
[task executeWithAppleEvent: nil completionHandler: ^(NSAppleEventDescriptor *result, NSError *error) {
NSLog(#"Finished task");
if (error) {
NSLog(#"Error running task: %#", error);
}
done = YES;
}];
// Wait until (done == YES). How??
}
return 0;
}
Now, I have three questions (which are the ones I want to ask with this SO entry). Firstly, "Finished task" never gets printed (the block never gets called) because the task never even starts executing. Instead, I get this on my console:
MessageTracer: msgtracer_vlog_with_keys:377: odd number of keys (domain: com.apple.automation.nsuserscripttask_run, last key: com.apple.message.signature)
I tried running the exact same code from the main app and it completes without a fuss (but from the main app I lose the ability to cancel the script).
Secondly, I only want to reach the end of main (return 0;) after the completion handler is called. But I have no idea how to do that.
Thridly, whenever there's an error or output from the helper I want to send that error/output back to the app, which will receive them through the errorPipe/outputPipe. Something like fprintf(stderr/stdout, "string") does the trick, but I'm not sure if it is the right way to do it.
So, in short, any help regarding the first and second problems is appreciated. The third one I just want to make sure that's how I'm supposed to do it.
Thanks
Question 1: The sub-task doesn't run because its parent exits immediately. (The log message about "odd number of keys" is a bug in NSUserScriptTask, and happens because your helper doesn't have a bundle identifier, but is otherwise harmless and irrelevant to your problem.) It exits immediately because it's not waiting for the completion block to fire, which brings us to...
Question 2: How do you wait for an asynchronous completion block? This has been answered elsewhere, including Wait until multiple networking requests have all executed - including their completion blocks, but to recap, use dispatch groups, something like this:
dispatch_group_t g = dispatch_group_create();
dispatch_group_enter(g);
[task executeWithAppleEvent:nil completionHandler:^(NSAppleEventDescriptor *result, NSError *e) {
...
dispatch_group_leave(g);
}];
dispatch_group_wait(g, DISPATCH_TIME_FOREVER);
dispatch_release(g);
This same pattern works for any call that has a completion block you want to wait for. If you wanted another notification when the group finishes instead of waiting for it, use dispatch_group_notify instead of dispatch_group_wait.
As a side note, the way you’re testing error after allocating the NSUserAppleScriptTask is incorrect. The value of error is defined if and only if the function result is nil (or NO, or whatever indicates failure). If the function succeeds (which you know if it returns non-nil), then error may be anything -- the function may set it to nil, it may leave it undefined, it may even fill it in with a real object. (See also What's the Point of (NSError**)error?)
I have a simple method run in background thread which open txt file and split it on lines. After that I'm trying to release memory, but something goes wrong. I'm using ARC. Here's code:
#autoreleasepool {
NSString* file = [NSString stringWithContentsOfFile:resourcePath encoding:NSWindowsCP1251StringEncoding error:&error];
NSArray* test = [file componentsSeparatedByString:#"\n"];
test = nil;
}
String released fine, but array still in memory. What I've missed?
UPD: Hm... Just tried to duplicate array few times, and after end of the method array really deallocates. But there is memory leak if I create this array. Where it could be?
// test = nil;
Dismiss it, and ARC will work fine.
-(void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag
{
[self NextHeading]; // this plays an mp3 file
[self NextHeadingMeaning]; // this plays an Mp3 file
}
Only [self NextHeadingMeaning] method is called and NextHeading method is missed each time
-(IBAction) NextHeading{
[audio stop];
NSString *Filename = [[NSString alloc]initWithFormat:#"CH%#S%#",Heading,Meaning];
Filepath = [[NSBundle mainBundle]pathForResource:Filename ofType:#"mp3"];
audio = [[AVAudioPlayer alloc]initWithContentsOfURL:[NSURL fileURLWithPath:Filepath] error:NULL];
audio.delegate = self;
[audio play];
[Filename autorelease];
}
-(IBAction) NextHeadingMeaning {
[audio stop];
NSString *Filename = [[NSString alloc] initWithFormat:#"CH%#S%#",bold**Chapter**bold, Meaning];
Filepath = [[NSBundle mainBundle]pathForResource:Filename ofType:#"mp3"];
audio = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:Filepath] error:NULL];
audio.delegate = self;
[audio play];
[Filename autorelease];
}
Why is this happening and how can I resolve it ?
Please advice, thanks in advance.
You just used a single iVar (audio) as an player, and when you send NextHeading & NextHeadingMeaning message, the audio init with your sound_1.mp3 file firstly (it'll take some seconds if the mp3 file is big), then at the next moment (your first mp3 file might not inited, or has inited, but stopped followed by next message), you redo the init action with another mp3 file (sound_2.mp3), and finally, when the second mp3 file init done, audio plays sound_2.mp3. That's why you think the NextHeading is skipped.
So, to solve this problem, you can use a NSMutableArray iVar (e.g. audioPlayers), and create a local audio for both NextHeading & NextHeadingMeaning, and push it to audioPlayers.
And I think it is better to preload sound files if you can. :)
EDIT:
There's a playAtTime: method instead of play, you can delay the second audio player's playing time by this method, just like this:
[audioPlayer playAtTime:(audioPlayer.deviceCurrentTime + delay)];
delay is in seconds (NSTimeInterval).
There is no way that the first call is skipped, put a breakpoint in it or output something with NSLog() and you'll see. Most probable cause is that the first method doesn't do what you expect and this could be for various reasons - for example condition or specific timeout.
Edit:
After looking your code, it seems that you're missing some basic stuff like variable naming, variable scope and so. To simply make your code run, just replace the NSString *Filename.. string from the second method and probably it'll work. A better choice would be to visit Start Developing iOS Apps Today and follow the roadmap.
I have a straightforward NSDocument-based Mac OS X app in which I am trying to implement iCloud Document storage. I'm building with the 10.7 SDK.
I have provisioned my app for iCloud document storage and have included the necessary entitlements (AFAICT). The app builds, runs, and creates the local ubiquity container Documents directory correctly (this took a while, but that all seems to be working). I am using the NSFileCoordinator API as Apple recommended. I'm fairly certain I am using the correct UbiquityIdentifier as recommended by Apple (it's redacted below tho).
I have followed Apple's iCloud Document storage demo instructions in this WWDC 2011 video closely:
Session 107 AutoSave and Versions in Lion
My code looks almost identical to the code from that demo.
However, when I call my action to move the current document to the cloud, I experience liveness problems when calling the -[NSFileManager setUbiquitous:itemAtURL:destinationURL:error:] method. It never returns.
Here is the relevant code from my NSDocument subclass. It is almost identical to Apple's WWDC demo code. Since this is an action, this is called on the main thread (as Apple's demo code showed). The deadlock occurs toward the end when the -setUbiquitous:itemAtURL:destinationURL:error: method is called. I have tried moving to a background thread, but it still never returns.
It appears that a semaphore is blocking while waiting for a signal that never arrives.
When running this code in the debugger, my source and destination URLs look correct, so I'm fairly certain they are correctly calculated and I have confirmed the directories exist on disk.
Am I doing anything obviously wrong which would lead to -setUbiquitous never returning?
- (IBAction)moveToOrFromCloud:(id)sender {
NSURL *fileURL = [self fileURL];
if (!fileURL) return;
NSString *bundleID = [[[NSBundle mainBundle] infoDictionary] objectForKey:#"CFBundleIdentifier"];
NSString *appID = [NSString stringWithFormat:#"XXXXXXX.%#.macosx", bundleID];
BOOL makeUbiquitous = 1 == [sender tag];
NSURL *destURL = nil;
NSFileManager *mgr = [NSFileManager defaultManager];
if (makeUbiquitous) {
// get path to local ubiquity container Documents dir
NSURL *dirURL = [[mgr URLForUbiquityContainerIdentifier:appID] URLByAppendingPathComponent:#"Documents"];
if (!dirURL) {
NSLog(#"cannot find URLForUbiquityContainerIdentifier %#", appID);
return;
}
// create it if necessary
[mgr createDirectoryAtURL:dirURL withIntermediateDirectories:NO attributes:nil error:nil];
// ensure it exists
BOOL exists, isDir;
exists = [mgr fileExistsAtPath:[dirURL relativePath] isDirectory:&isDir];
if (!(exists && isDir)) {
NSLog(#"can't create local icloud dir");
return;
}
// append this doc's filename
destURL = [dirURL URLByAppendingPathComponent:[fileURL lastPathComponent]];
} else {
// get path to local Documents folder
NSArray *dirs = [mgr URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask];
if (![dirs count]) return;
// append this doc's filename
destURL = [[dirs objectAtIndex:0] URLByAppendingPathComponent:[fileURL lastPathComponent]];
}
NSFileCoordinator *fc = [[[NSFileCoordinator alloc] initWithFilePresenter:self] autorelease];
[fc coordinateWritingItemAtURL:fileURL options:NSFileCoordinatorWritingForMoving writingItemAtURL:destURL options:NSFileCoordinatorWritingForReplacing error:nil byAccessor:^(NSURL *fileURL, NSURL *destURL) {
NSError *err = nil;
if ([mgr setUbiquitous:makeUbiquitous itemAtURL:fileURL destinationURL:destURL error:&err]) {
[self setFileURL:destURL];
[self setFileModificationDate:nil];
[fc itemAtURL:fileURL didMoveToURL:destURL];
} else {
NSWindow *win = ... // get my window
[self presentError:err modalForWindow:win delegate:nil didPresentSelector:nil contextInfo:NULL];
}
}];
}
I don't know if these are the source of your problems, but here are some things I'm seeing:
-[NSFileManager URLForUbiquityContainerIdentifier:] may take a while, so you shouldn't invoke it on the main thread. see the "Locating the Ubiquity Container" section of this blog post
Doing this on the global queue means you should probably use an allocated NSFileManager and not the +defaultManager.
The block passed to the byAccessor portion of the coordinated write is not guaranteed to be called on any particular thread, so you shouldn't be manipulating NSWindows or presenting modal dialogs or anything from within that block (unless you've dispatched it back to the main queue).
I think pretty much all of the iCloud methods on NSFileManager will block until things complete. It's possible that what you're seeing is the method blocking and never returning because things aren't configured properly. I'd double and triple check your settings, maybe try to simplify the reproduction case. If it still isn't working, try filing a bug or contacting DTS.
Just shared this on Twitter with you, but I believe when using NSDocument you don't need to do any of the NSFileCoordinator stuff - just make the document ubiquitous and save.
Hmm,
did you try not using a ubiquity container identifier in code (sorry - ripped out of a project so I've pseudo-coded some of this):
NSFileManager *fm = [NSFileManager defaultManager];
NSURL *iCloudDocumentsURL = [[fm URLForUbiquityContainerIdentifier:nil] URLByAppendingPathComponent:#"Documents"];
NSURL *iCloudFileURL = [iCloudDocumentsURL URLByAppendingPathComponent:[doc.fileURL lastPathComponent]];
ok = [fm setUbiquitous:YES itemAtURL:doc.fileURL destinationURL:iCloudRecipeURL error:&err];
NSLog(#"doc moved to iCloud, result: %d (%#)",ok,doc.fileURL.fileURL);
And then in your entitlements file:
<key>com.apple.developer.ubiquity-container-identifiers</key>
<array>
<string>[devID].com.yourcompany.appname</string>
</array>
Other than that, your code looks almost identical to mine (which works - except I'm not using NSDocument but rolling it all myself).
If this is the first place in your code that you are accessing iCloud look in Console.app for a message like this:
taskgated: killed yourAppID [pid 13532] because its use of the com.apple.developer.ubiquity-container-identifiers entitlement is not allowed
Anytime you see this message delete your apps container ~/Library/Containers/<yourAppID>
There may also be other useful messages in Console.app that will help you solve this issue.
I have found that deleting the app container is the new Clean Project when working with iCloud.
Ok, So I was finally able to solve the problem using Dunk's advice. I'm pretty sure the issue I was having is as follows:
Sometime after the WWDC video I was using as a guide was made, Apple completed the ubiquity APIs and removed the need to use an NSFileCoordinator object while saving from within an NSDocument subclass.
So the key was to remove both the creation of the NSFileCoordinator and the call to -[NSFileCoordinator coordinateWritingItemAtURL:options:writingItemAtURL:options:error:byAccessor:]
I also moved this work onto a background thread, although I'm fairly certain that was not absolutely required to fix the issue (although it was certainly a good idea).
I shall now submit my completed code to Google's web crawlers in hopes of assisting future intrepid Xcoders.
Here's my complete solution which works:
- (IBAction)moveToOrFromCloud:(id)sender {
NSURL *fileURL = [self fileURL];
if (!fileURL) {
NSBeep();
return;
}
BOOL makeUbiquitous = 1 == [sender tag];
if (makeUbiquitous) {
[self displayMoveToCloudDialog];
} else {
[self displayMoveFromCloudDialog];
}
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[self doMoveToOrFromCloud:makeUbiquitous];
});
}
- (void)doMoveToOrFromCloud:(BOOL)makeUbiquitous {
NSURL *fileURL = [self fileURL];
if (!fileURL) return;
NSURL *destURL = nil;
NSFileManager *mgr = [[[NSFileManager alloc] init] autorelease];
if (makeUbiquitous) {
NSURL *dirURL = [[MyDocumentController instance] ubiquitousDocumentsDirURL];
if (!dirURL) return;
destURL = [dirURL URLByAppendingPathComponent:[fileURL lastPathComponent]];
} else {
// move to local Documentss folder
NSArray *dirs = [mgr URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask];
if (![dirs count]) return;
destURL = [[dirs firstObject] URLByAppendingPathComponent:[fileURL lastPathComponent]];
}
NSError *err = nil;
void (^completion)(void) = nil;
if ([mgr setUbiquitous:makeUbiquitous itemAtURL:fileURL destinationURL:destURL error:&err]) {
[self setFileURL:destURL];
[self setFileModificationDate:nil];
completion = ^{
[self hideMoveToFromCloudDialog];
};
} else {
completion = ^{
[self hideMoveToFromCloudDialog];
NSWindow *win = [[self canvasWindowController] window];
[self presentError:err modalForWindow:win delegate:nil didPresentSelector:nil contextInfo:NULL];
};
}
dispatch_async(dispatch_get_main_queue(), completion);
}
I am trying to call objectForKey: on an nsdictionary ivar, but I get an EXC_BAD_ACCESS error.
The nsdictionary is created using the JSON-framework and then retained. The first time I use it (just after I create it, same run loop) it works perfectly fine, but when I try to access it later nothing works. I am doing this code to try to figure out what is wrong:
if (resultsDic == nil) {
NSLog(#"results dic is nil.");
}
if ( [resultsDic respondsToSelector:#selector(objectForKey:)] ) {
NSLog(#"resultsDic should respond to objectForKey:");
}
The dictionary is never nil, but it always crashes on respondsToSelector. any ideas?
addition:
These are the other places, besides above, that the dictionary gets interacted with:
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
[connection release];
//get the data in a usable form
NSString *jsonString = [[NSString alloc] initWithData:downloadedData encoding:NSUTF8StringEncoding];
resultsDic = [jsonString JSONValue];
[self processResults];
NSLog(#"Success. Received %d bytes of data",[downloadedData length]);
[downloadedData release];
[jsonString release];
}
- (void)processResults
{
NSArray *resultsArr = [resultsDic objectForKey:#"results"];
CLLocationCoordinate2D coordinate = [self coordinateFromResult:[resultsArr objectAtIndex:0]];
NSLog(#"lat: %f lng: %f", coordinate.latitude, coordinate.longitude);
}
- (void)dealloc {
[resultsDic release];
[super dealloc];
}
After somethings retain count is decreased to 0, the object gets deallocated. This is not the same as setting it to nil. It will not be nil. Whilst you can send messages to nil, sending a message to a released object will result in an EXC_BAD_ACCESS error. If you post some of the code where it is created and used, maybe we can help you debug it. Try retaining it twice at the beginning. it's nit an elegant solution, but it might work as a quick fix.
Sounds like a classic zombie. Run it again with the environment variable NSZombieEnabled set to YES (or use the Zombies instrument in Instruments.app). That should give you much more information about what's going on.