Random EXC_BAD_ACCESS (code=1, address=0x4) when multithreading on iOS - ios

Question

I have a case, when I get EXC_BAD_ACCESS (code=1, address=0x4) exception randomly, when calling method with multi threads. Same method, sometime error accure, sometimes don't. But my measurements show that at least 1 out of 5 runs will produce this error.
Firstly let me show a diagram how my code is organized, so it will be easier to read the code.
I have one View controller that handle the view and call server class (instance stored in AppDelegate class) for data. Data there is retrieved from server asynchronously and store in Core data DB and call CompleteHandler when it is done.
In between, delegate method in server is called to update progress percentage in ViewControllers.
After this is done, ViewController call build Model class that is build asynchronously, and read data from Core data DB.
In this step, when model is called to build, error occurs.
Second problem is that even that delegate method is called and right percentage is send to ViewController, progress bar is not updated.
This, and fact that error come randomly, let me believe that it has to be something wrong with threading and that some object is released to soon.
I try debug with Zombies, but nothing shows up.
CODE :
ViewController
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// THIS IS NOTIFICATIONS FROM MODEL
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(modelProgressUpdate:) name:ProcessUpdateNotification object:nil];
self.coreDataQueue = dispatch_queue_create("com.my.core.data", NULL);
[self download1];
}
#pragma mark - Progres bar
// METHOD THAT IS CALLED AFTER NSNOTIFICATION IS CALLED
- (void) modelProgressUpdate:(NSNotification * ) notification{
BINotificationsProcessUpdate * update = (BINotificationsProcessUpdate * )notification.object;
[self updateProgressWithPercent:update.percent];
}
- (void) modelPrograssCancel
{
[self.progressViewContainer layoutSubviews];
[UIView animateWithDuration:0.5 animations:^{
self.ProgressViewTopConstraint.constant = -15;
[self.progressViewContainer layoutSubviews];
[self.view layoutSubviews];
}];
self.ProgressView.progress = 0;
}
// METHODS THAT ARE CALLED WITH SERVER DELEGATES
- (void) cancelProgresView
{
[self modelPrograssCancel];
}
- (void) progressInProcentage1:(float)procentage{
__weak ViewController * weekSelf = self;
dispatch_async(dispatch_get_main_queue(), ^(void) {
[weekSelf updateProgressWithPercent:procentage];
});
}
- (void) progressInProcentage2:(float)procentage{
__weak ViewController * weekSelf = self;
dispatch_async(dispatch_get_main_queue(), ^(void) {
[weekSelf updateProgressWithPercent:procentage];
});
}
- (void) updateProgressWithPercent: (float) percent
{
if (self.ProgressViewTopConstraint.constant != 0) {
[self.progressViewContainer layoutSubviews];
[UIView animateWithDuration:0.5 animations:^{
self.ProgressViewTopConstraint.constant = 0;
[self.progressViewContainer layoutSubviews];
[self.view layoutSubviews];
}];
}
self.ProgressView.progress = percent;
}
#pragma mark - download data
-(void)download1{
__weak ViewController * weekSelf = self;
// build new NSManagedObjectContext
weekSelf.backgroundManagedObjectContext = [[NSManagedObjectContext alloc]init];
[weekSelf.backgroundManagedObjectContext setPersistentStoreCoordinator:[[ManagedContextHelper getManagedObjectContext] persistentStoreCoordinator]];
[[NSNotificationCenter defaultCenter] addObserver:weekSelf selector:#selector(backgroundContextDidSave:) name:NSManagedObjectContextDidSaveNotification object:weekSelf.backgroundManagedObjectContext];
AppDelegate * appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
[appDelegate.serverConnection callGet1:weekSelf.server managedObjectContext:weekSelf.backgroundManagedObjectContext delegate:weekSelf withCompletionHandler:^(BIResponseObject *response) {
switch (response.responseType) {
case BIResponseTypeNoInternet:
case BIResponseTypeConnectionTimeOut:
[weekSelf cancelProgresView];
break;
case BIResponseTypeOK:
[weekSelf download2];
break;
default:
[weekSelf loadModel];
[weekSelf noServerWarrning];
break;
}
}];
}
-(void)download2{
__weak ViewController * weekSelf = self;
AppDelegate * appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
[appDelegate.serverConnection callGet2:weekSelf.server managedObjectContext:weekSelf.backgroundManagedObjectContext delegate:weekSelf withCompletionHandler:^(BIResponseObject *response) {
switch (response.responseType) {
case BIResponseTypeFactTableOK: {
weekSelf.object.downlodedDate = [NSDate date];
[weekSelf.object save:weekSelf.backgroundManagedObjectContext];
[weekSelf loadModel];
[[ManagedContextHelper getManagedObjectContext] save:nil];
}
case BIResponseTypeConnectionTimeOut:
case BIResponseTypeNoInternet:
case BIResponseTypeFactTableError:
[weekSelf cancelProgresView];
break;
default:
[weekSelf cancelProgresView];
break;
}
}];
}
#pragma mark - LOAD MODEL
-(void)loadModel{
__weak ViewController * weekSelf = self;
dispatch_async(weekSelf.coreDataQueue, ^(void){
// build new NSManagedObjectContext
if (!weekSelf.backgroundManagedObjectContext) {
weekSelf.backgroundManagedObjectContext = [[NSManagedObjectContext alloc]init];
[weekSelf.backgroundManagedObjectContext setPersistentStoreCoordinator:[[ManagedContextHelper getManagedObjectContext] persistentStoreCoordinator]];
[[NSNotificationCenter defaultCenter] addObserver:weekSelf selector:#selector(backgroundContextDidSave:) name:NSManagedObjectContextDidSaveNotification object:weekSelf.backgroundManagedObjectContext];
}
MyUIObject * uiObject = [DataBase getUIObject:weekSelf.backgroundManagedObjectContext];
weekSelf.myObject = [[UIScrollObject alloc] initWith: uiObject];
weekSelf.myObject.delegate = weekSelf;
if (uiObject && weekSelf.myObject) {
dispatch_async(dispatch_get_main_queue(), ^(void) {
self.myObject.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:self.myObject];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"H:|[_myObject]|" options:NSLayoutFormatDirectionLeadingToTrailing metrics:nil views:NSDictionaryOfVariableBindings(_myObject)]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"V:|-(66)-[_myObject]|" options:NSLayoutFormatDirectionLeadingToTrailing metrics:nil views:NSDictionaryOfVariableBindings(_myObject)]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.myObject attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeWidth multiplier:1 constant:0]];
[self.view sendSubviewToBack:self.myObject];
// Add model
[self.myObject createModel]; // THIS IS A LINE THAT I THINK IT BREAK,... logs are till here.
});
}
else {
[weekSelf dissmisView:weekSelf];
}
});
}
- (void) dissmisView: (ViewController * ) selfReference {
dispatch_async(dispatch_get_main_queue(), ^(void) {
[selfReference cancelProgresView];
if (![selfReference.presentedViewController isBeingDismissed]) {
[selfReference dismissViewControllerAnimated:YES completion:nil];
}
});
}
#pragma mark - handling multi ManagedObjectContext
- (void)backgroundContextDidSave:(NSNotification *)notification {
/* Make sure we're on the main thread when updating the main context */
if (![NSThread isMainThread]) {
[self performSelectorOnMainThread:#selector(backgroundContextDidSave:)
withObject:notification
waitUntilDone:NO];
return;
}
/* merge in the changes to the main context */
[[ManagedContextHelper getManagedObjectContext] mergeChangesFromContextDidSaveNotification:notification];
}
...
#end
MODEL created
dispatch_async(self.model_queue, ^(void){
// Create Model in new thread
[self createPrimaryModel_newThread]; // inside here notifications are send to update progress bar.
/// Model is complete
[BINotifications notifyModelIsCompletedCreating:self];
});
BINotifications
+ (void) notifyProgressUpdateWithPercent: (float) percent andNotificationString: (NSString * ) notificationString {
dispatch_async(dispatch_get_main_queue(), ^(void) {
[[NSNotificationCenter defaultCenter] postNotificationName:ProcessUpdateNotification
object:[[BINotificationsProcessUpdate alloc]
initWithPercent:percent
description:notificationString]];
});
}
Server class
-(void)callGet2: (Server *) server managedObjectContext: (NSManagedObjectContext *)managedObjectContext delegate: (id) delegate withCompletionHandler:(void (^)(BIResponseObject * response))callback
{
id<BIServerConnectionDelegate> _delegate = delegate;
[_delegate progressInProcentage2:0.0];
NSString * method = [NSString stringWithFormat:#".../%i", ...];
[self callServerWithMethod:method server:server withCallBack:^(BIResponseObject *response) {
[_delegate progressInProcentage2:0.3];
// parse
response.responseType = [self parse2:response server:server managedObjectContext:managedObjectContext delegate:_delegate];
[self setResponseTitleAndMessage:response server:server];
callback(response);
}];
}
I know it is a lot, but I am really stuck with it.
Code is "cleaned", so name of functions,... are changed (I can't reveal real code.), so I know the names are not ok :D, but code is real.