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PODetermining the root cause of an EXC_BAD_ACCESS without NSZombie?
 

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  1. PODetermining the root cause of an EXC_BAD_ACCESS without NSZombie?
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    <p>Thank you in advance for any help/insight you can give into the issue I am having. Just recently my iOS app began to fail with the dreaded <code>EXC_BAD_ACCESS</code> error. I did a lot of research on SO and Google and received some great advice, but none of the posts have helped me to resolve my issue. By now, I understand that EXC_BAD_ACCESS could be one of two things:</p> <pre><code>1) A pointer is now pointing to memory that was deallocated. 2) A pointer itself is corrupt. </code></pre> <p>I read and followed the instructions <a href="https://stackoverflow.com/questions/3111585/tracking-down-exc-bad-access-without-nszombie">here</a>, <a href="http://loufranco.com/blog/files/Understanding-EXC_BAD_ACCESS.html" rel="nofollow noreferrer">here</a>, <a href="https://stackoverflow.com/questions/327082/exc-bad-access-signal-received">here</a>, and <a href="http://mobiledevelopertips.com/debugging/tracking-down-exc_bad_access-errors-with-nszombieenabled.html" rel="nofollow noreferrer">here</a>. When I perform "Build and Run" I can reproduce the exc_bad_access 100% of the time. However, when I enabled NSZombie in either the debugger or in Instruments, I <strong>never</strong> can reproduce the issue. Furthermore, NSZombie does not leave any helpful information in the console.</p> <p>The closest I got to pinpointing the issue was by literally putting an NSLog after every single line of code, in order to see where it was crashing. I believe that it is crashing at two distinct points - both of which are returning a cell in the <code>cellForRowAtIndexPath</code>. Below I'm providing the two methods where I believe things are crashing, as well as the error output on my console. Any help or guidance would be greatly appreciated, thanks!</p> <p>The offending method:</p> <pre><code>- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { if (indexPath.section == 0) { static NSString *CellIdentifier = @"EventDetailCell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; cell.textLabel.textColor = [UIColor colorWithRed:150 green:143 blue:135 alpha:1.0]; cell.textLabel.highlightedTextColor = [UIColor whiteColor]; cell.textLabel.font = [UIFont fontWithName:@"Helvetica" size:15]; if (indexPath.row &lt; 4) { UIImageView *disclosureArrow = [[UIImageView alloc] initWithFrame:CGRectMake(280, 15, 10, 14)]; disclosureArrow.image = [UIImage imageNamed:@"tableRowAccessoryArrow"]; [cell.contentView addSubview:disclosureArrow]; } } else { if ((indexPath.section == 0) &amp;&amp; (indexPath.row == 4)) { for (UIView *v in [cell.contentView subviews]) { [v removeFromSuperview]; } } } switch (indexPath.row) { case 0: cell.textLabel.text = [NSString stringWithFormat:@"%@", self.startTime]; cell.backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"eventDetailRowTop"]]; cell.imageView.image = [UIImage imageNamed:@"clockIcon"]; break; case 1: cell.textLabel.text = @"Location"; cell.backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"eventDetailRowMiddle"]]; cell.selectedBackgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"eventDetailRowMiddleSelected"]]; cell.imageView.image = [UIImage imageNamed:@"mapIcon"]; break; case 2: cell.textLabel.text = [NSString stringWithFormat:@"%u attendees", [self.attendees count]]; cell.backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"eventDetailRowMiddle"]]; cell.selectedBackgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"eventDetailRowMiddleSelected"]]; cell.imageView.image = [UIImage imageNamed:@"attendeesIcon"]; break; case 3: cell.textLabel.text = [NSString stringWithFormat:@"%u fomos", [self.fomos count]]; cell.backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"eventDetailRowBottom"]]; cell.selectedBackgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"eventDetailRowMiddleSelected"]]; cell.imageView.image = [UIImage imageNamed:@"fomoIcon"]; break; case 4: { cell.selectionStyle = UITableViewCellSelectionStyleNone; UIImage *clockIcon = [UIImage imageNamed:@"clockIcon"]; UIImageView *iconSlot = [[UIImageView alloc] initWithFrame:CGRectMake(3, 18, 18, 18)]; iconSlot.image = clockIcon; [cell.contentView addSubview:iconSlot]; NSString *currentTime = @"Happening Now"; UILabel *currentTimeLabel = [[UILabel alloc] initWithFrame:CGRectMake(25, 8, 150, 36)]; currentTimeLabel.backgroundColor = [UIColor clearColor]; currentTimeLabel.textColor = [UIColor whiteColor]; currentTimeLabel.font = [UIFont fontWithName:@"Helvetica" size:14]; currentTimeLabel.text = currentTime; [cell.contentView addSubview:currentTimeLabel]; UIImage *listView = [UIImage imageNamed:@"listViewSelected"]; self.listViewButton = [UIButton buttonWithType:UIButtonTypeCustom]; self.listViewButton.frame = CGRectMake(180, 8, 36, 36); self.listViewButton.tag = 1; [self.listViewButton addTarget:self action:@selector(togglePhotosView:) forControlEvents:UIControlEventTouchUpInside]; [self.listViewButton setBackgroundImage:listView forState:UIControlStateNormal]; [cell.contentView addSubview:self.listViewButton]; UIImage *gridView = [UIImage imageNamed:@"gridViewIcon"]; self.gridViewButton = [UIButton buttonWithType:UIButtonTypeCustom]; self.gridViewButton.frame = CGRectMake(240, 7.2f, 36, 36); self.gridViewButton.tag = 2; [self.gridViewButton addTarget:self action:@selector(togglePhotosView:) forControlEvents:UIControlEventTouchUpInside]; [self.gridViewButton setBackgroundImage:gridView forState:UIControlStateNormal]; [cell.contentView addSubview:self.gridViewButton]; break; } default: break; } return cell; } else { if ([self.listViewObjects count] == 0) { // Do something when there are no pictures or stories to show static NSString *CellIdentifier = @"NoPhotosYetCell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; cell.textLabel.textColor = [UIColor colorWithRed:0.150 green:0.143 blue:0.135 alpha:1.0]; cell.textLabel.highlightedTextColor = [UIColor whiteColor]; cell.selectionStyle = UITableViewCellSelectionStyleNone; cell.textLabel.text = @"No photos have been added yet."; } return cell; } else { if (self.isGridView == YES) { static NSString *CellIdentifier = @"EventContentGridViewCell"; EventDetailGridRow *cell = (EventDetailGridRow *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[EventDetailGridRow alloc] initWithFrame:CGRectMake(0, 0, 306, 102)]; cell.backgroundColor = [UIColor redColor]; } NSMutableArray *mutablePhotos = [NSMutableArray arrayWithArray:self.photos]; int offset = (indexPath.row * 3); int maxRange = 3; if (([mutablePhotos count] &lt; (offset + maxRange))) { maxRange = ([mutablePhotos count] - offset); } NSArray *firstThree = [mutablePhotos subarrayWithRange:NSMakeRange(offset, maxRange)]; cell.photos = firstThree; return cell; } else { static NSString *CellIdentifier = @"EventContentListViewCell"; EventDetailListRowCell *cell = (EventDetailListRowCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[EventDetailListRowCell alloc] initWithFrame:CGRectMake(0, 0, 306, 400)]; } NSString *authorName; NSString *authorUID; BOOL isPhoto = YES; if ([[self.listViewObjects objectAtIndex:indexPath.row] valueForKey:@"caption"] != nil) { // It's a photo object NSDictionary *photo = [self.listViewObjects objectAtIndex:indexPath.row]; NSString *photoID = [photo valueForKey:@"id"]; NSString *photoName = [photo valueForKey:@"image_file_name"]; NSURL *photoURL = [NSURL URLWithString:[NSString stringWithFormat:@"http://s3.amazonaws.com/motlee-development-photos/images/%@/compressed/%@", photoID, photoName]]; authorName = [photo valueForKeyPath:@"owner.name"][0]; authorUID = [photo valueForKeyPath:@"owner.uid"][0]; UIImageView *imageContainer = [[UIImageView alloc] initWithFrame:CGRectMake(0, 20, 300, 300)]; [imageContainer setImageWithURL:photoURL]; [cell.contentView addSubview:imageContainer]; } else if ([[self.listViewObjects objectAtIndex:indexPath.row] valueForKey:@"body"] != nil) { isPhoto = NO; NSDictionary *story = [self.listViewObjects objectAtIndex:indexPath.row]; authorName = [story valueForKeyPath:@"owner.name"][0]; authorUID = [story valueForKeyPath:@"owner.uid"][0]; UIImageView *imageContainer = [[UIImageView alloc] initWithFrame:CGRectMake(0, 20, cell.frame.size.width, 148)]; imageContainer.image = [UIImage imageNamed:@"storyContainer"]; [cell.contentView addSubview:imageContainer]; UILabel *storyBody = [[UILabel alloc] initWithFrame:CGRectMake(30, 20, (306 - 60), 148)]; storyBody.numberOfLines = 3; storyBody.backgroundColor = [UIColor clearColor]; storyBody.textAlignment = NSTextAlignmentCenter; storyBody.font = [UIFont fontWithName:@"Helvetica" size:17]; storyBody.textColor = [UIColor whiteColor]; storyBody.text = [NSString stringWithFormat:@"\"%@\"", [story valueForKey:@"body"]]; [cell.contentView addSubview:storyBody]; } else { // Something screwy going on here, should have been one of the above objects } NSURL *profilePicURL = [NSURL URLWithString:[NSString stringWithFormat:@"http://graph.facebook.com/%@/picture", authorUID]]; UIImageView *profilePic; if (isPhoto) profilePic = [[UIImageView alloc] initWithFrame:CGRectMake(20, 347, 40, 40)]; else profilePic = [[UIImageView alloc] initWithFrame:CGRectMake(20, 179, 40, 40)]; [profilePic setImageWithURL:profilePicURL placeholderImage:[UIImage imageNamed:@"placeholder"]]; [cell.contentView addSubview:profilePic]; UILabel *takenByLabel; if (isPhoto) { takenByLabel = [[UILabel alloc] initWithFrame:CGRectMake(70, 342, 170, 30)]; } else { takenByLabel = [[UILabel alloc] initWithFrame:CGRectMake(70, 174, 170, 30)]; } takenByLabel.textColor = [UIColor lightGrayColor]; takenByLabel.font = [UIFont fontWithName:@"Helvetica" size:12]; takenByLabel.backgroundColor = [UIColor clearColor]; if (isPhoto) takenByLabel.text = @"taken by"; else takenByLabel.text = @"written by"; [cell.contentView addSubview:takenByLabel]; UILabel *photoTakerLabel; if (isPhoto) { photoTakerLabel = [[UILabel alloc] initWithFrame:CGRectMake(70, 360, 170, 30)]; } else { photoTakerLabel = [[UILabel alloc] initWithFrame:CGRectMake(70, 192, 170, 30)]; } photoTakerLabel.textColor = [UIColor whiteColor]; photoTakerLabel.font = [UIFont fontWithName:@"Helvetica" size:14]; photoTakerLabel.backgroundColor = [UIColor clearColor]; photoTakerLabel.text = authorName; [cell.contentView addSubview:photoTakerLabel]; return cell; } } } } </code></pre> <p>The log output:</p> <pre><code>libobjc.A.dylib`objc_msgSend: 0x1f5908c: movl 8(%esp), %ecx 0x1f59090: movl 4(%esp), %eax 0x1f59094: testl %eax, %eax 0x1f59096: je 0x1f590e8 ; objc_msgSend + 92 0x1f59098: movl (%eax), %edx 0x1f5909a: pushl %edi 0x1f5909b: movl 8(%edx), %edi &lt;-- EXC_BAD_ACCESS (code=2, address=0xb0000008) </code></pre>
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    1. USCommunity
    1. USScott Lieberman
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      1. VTUpMod
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      1. VTUpMod
    1. COYou haven't been able to get the specific line on which the crash happens, or it varies too much to be able to tell you the solution? Nowadays Apple seem to require you manually to add an exception breakpoint to catch the exact line if that's preventing that. The specific line would be a helpful clue in figuring out what's going on overall.
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      1. PODetermining the root cause of an EXC_BAD_ACCESS without NSZombie?
      1. USTommy
    2. COThat's way too much code for anyone to wade through based on your hunch about where the error is. You should add an exception breakpoint as Tommy suggested, and see if that will point you to the offending line of code.
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      1. PODetermining the root cause of an EXC_BAD_ACCESS without NSZombie?
      1. USrdelmar
    3. CO@Tommy, I haven't been able to get the specific line. When I put the NSLogs into the code, it was always crashing around two different places. However, both of those places were returning a cell in the cellForRowAtIndexPath method.
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      1. PODetermining the root cause of an EXC_BAD_ACCESS without NSZombie?
      1. USScott Lieberman
 

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