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POMultithreading problem: code crashes at specific point
 

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  1. POMultithreading problem: code crashes at specific point
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    <p>I just introduced multithreading into my app, and now it crashes at a specific point in the program, whilst if I don't do multithreading it does work.</p> <p>FlipsideViewController.h</p> <pre><code>// // FlipsideViewController.h // iRSG // // Created by Thomas van Arkel on 12-02-11. // Copyright 2011 Arques Software. All rights reserved. // #import &lt;UIKit/UIKit.h&gt; @protocol FlipsideViewControllerDelegate; @interface FlipsideViewController : UIViewController { id &lt;FlipsideViewControllerDelegate&gt; delegate; NSArray *timeTableArray; IBOutlet UIActivityIndicatorView *activityIndicator; } - (IBAction)getTimeTable:(UIButton *)sender; - (IBAction)removeTimeTable:(UIButton *)sender; @property (nonatomic, assign) id &lt;FlipsideViewControllerDelegate&gt; delegate; - (IBAction)done:(id)sender; @end @protocol FlipsideViewControllerDelegate - (void)flipsideViewControllerDidFinish:(FlipsideViewController *)controller; @end </code></pre> <p>FlipsideViewController.m</p> <pre><code>// // FlipsideViewController.m // iRSG // // Created by Thomas van Arkel on 12-02-11. // Copyright 2011 Arques Software. All rights reserved. // #import "FlipsideViewController.h" #import "TimeTableCreator.h" #import "Lesson.h" #import "iRSGAppDelegate.h" @interface FlipsideViewController() @property (nonatomic, retain) IBOutlet UIActivityIndicatorView *spinner; @end @implementation FlipsideViewController @synthesize delegate; @synthesize spinner; - (void)viewDidLoad { [super viewDidLoad]; self.view.backgroundColor = [UIColor groupTableViewBackgroundColor]; } - (IBAction)done:(id)sender { [self.delegate flipsideViewControllerDidFinish:self]; } - (IBAction)getTimeTable:(UIButton *)sender { activityIndicator = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray]; activityIndicator.frame = CGRectMake(0.0, 0.0, 40.0, 40.0); activityIndicator.center = self.view.center; [self.view addSubview: activityIndicator]; [activityIndicator startAnimating]; dispatch_queue_t downloadQueue = dispatch_queue_create("TimeTable downloader", NULL); timeTableArray = [[NSArray alloc] init]; dispatch_async(downloadQueue, ^{ NSString* settingValue = [[NSUserDefaults standardUserDefaults] stringForKey:@"partOfSchool"]; if ([settingValue isEqualToString:@"upper"]) { NSString *studentID = [[NSUserDefaults standardUserDefaults] stringForKey:@"studentID"]; NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http://roosters.rsgslingerboslevant.nl/lichtkrant/slingerbos/leerlingen/ll_roost_%@.htm", studentID]]; timeTableArray = [TimeTableCreator createTimeTableWithURL:url]; } else if ([settingValue isEqualToString:@"lower"]) { NSString *class = [[NSUserDefaults standardUserDefaults] stringForKey:@"class"]; if (class.length == 2) { NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http://roosters.rsgslingerboslevant.nl/lichtkrant/Slingerbos/Klassen/K_%@.htm", class]]; timeTableArray = [TimeTableCreator createTimeTableForLowerClassWithURL:url]; } else if (class.length == 3) { NSString *beginningString = [class substringToIndex:1]; NSString *endString = [class substringFromIndex:2]; endString = [endString lowercaseString]; class = [beginningString stringByAppendingString:endString]; NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http://roosters.rsgslingerboslevant.nl/lichtkrant/Slingerbos/Klassen/K_%@.htm", class]]; timeTableArray = [TimeTableCreator createTimeTableForLowerClassWithURL:url]; } } dispatch_async(dispatch_get_main_queue(), ^{ NSManagedObjectContext *managedObjectContext = nil; if (managedObjectContext == nil) { iRSGAppDelegate *appDelegate = (iRSGAppDelegate *)[[UIApplication sharedApplication] delegate]; managedObjectContext = [appDelegate managedObjectContext]; } NSFetchRequest * allLessons = [[NSFetchRequest alloc] init]; [allLessons setEntity:[NSEntityDescription entityForName:@"Lesson" inManagedObjectContext:managedObjectContext]]; [allLessons setIncludesPropertyValues:NO]; //only fetch the managedObjectID NSError * error = nil; NSArray * lessons = [managedObjectContext executeFetchRequest:allLessons error:&amp;error]; NSLog(@"Amount of lessons is %@", [NSNumber numberWithInt:[lessons count]]); [allLessons release]; //error handling goes here for (NSManagedObject * lesson in lessons) { [managedObjectContext deleteObject:lesson]; } iRSGAppDelegate *appDelegate = (iRSGAppDelegate *)[[UIApplication sharedApplication] delegate]; [appDelegate saveContext]; [appDelegate saveContext]; for (NSArray *lessonArray in timeTableArray) { [Lesson lessonWithLessonArray:lessonArray inManagedObjectContext:managedObjectContext]; } UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:@"Het rooster is succesvol geïmporteerd"delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil]; [alert show]; [alert release]; [activityIndicator stopAnimating]; }); }); dispatch_release(downloadQueue); } - (IBAction)removeTimeTable:(UIButton *)sender { NSManagedObjectContext *managedObjectContext = nil; if (managedObjectContext == nil) { iRSGAppDelegate *appDelegate = (iRSGAppDelegate *)[[UIApplication sharedApplication] delegate]; managedObjectContext = [appDelegate managedObjectContext]; } NSFetchRequest * allLessons = [[NSFetchRequest alloc] init]; [allLessons setEntity:[NSEntityDescription entityForName:@"Lesson" inManagedObjectContext:managedObjectContext]]; [allLessons setIncludesPropertyValues:NO]; //only fetch the managedObjectID NSError * error = nil; NSArray * lessons = [managedObjectContext executeFetchRequest:allLessons error:&amp;error]; NSLog(@"Amount of lessons is %@", [NSNumber numberWithInt:[lessons count]]); [allLessons release]; //error handling goes here for (NSManagedObject * lesson in lessons) { [managedObjectContext deleteObject:lesson]; } iRSGAppDelegate *appDelegate = (iRSGAppDelegate *)[[UIApplication sharedApplication] delegate]; [appDelegate saveContext]; } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } /* // Override to allow orientations other than the default portrait orientation. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } */ - (void)dealloc { [super dealloc]; } @end </code></pre> <p>The program always crashes here</p> <pre><code> for (NSArray *lessonArray in timeTableArray) { [Lesson lessonWithLessonArray:lessonArray inManagedObjectContext:managedObjectContext]; } </code></pre> <p>Thanks in advance</p> <p><strong>EDIT</strong> Source code <a href="http://cl.ly/3k322a472A0Q0A3F0S1G" rel="nofollow">http://cl.ly/3k322a472A0Q0A3F0S1G</a></p> <p>To test it, in settings app enter '2007042' in for 'leerlingnummer' and for 'onder/bovenbouw' choose 'bovenbouw' (sorry for the fact that it is in Dutch, I'm writing the code for a Dutch school</p> <p>I get a EXC_BAD_ACCESS error, nothing is on the console. <strong>SOLVED</strong> I made a new timeTableArray property and when setting the array, i used self.timeTableArray. This was why it said that it was deallocated (thanks to NSZombie)</p>
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    1. COcan you please post what error you are getting?
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    2. COI get a EXC_BAD_ACCESS error, and nothing is on the console
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      1. USthvanarkel
 

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