提前感谢您提供有关我所遇到的问题的任何帮助/见解。就在最近，我的iOS应用程序因可怕的EXC_BAD_ACCESS错误而开始失败。我对SO和Google进行了大量研究，并收到了一些很好的建议，但这些帖子都没有帮助我解决我的问题。到目前为止，我知道EXC_BAD_ACCESS可能是两件事之一：
1) A pointer is now pointing to memory that was deallocated.
2) A pointer itself is corrupt.
我阅读并按照说明here，here，here和here进行操作。当我执行“构建并运行”时，我可以100％重现exc_bad_access。但是，当我在调试器或工具中启用NSZombie时，我从不可以重现该问题。此外，NSZombie不会在控制台中留下任何有用的信息。
我最接近确定问题的方法是在每一行代码之后放置一个NSLog，以便查看崩溃的位置。我相信它会在两个不同的点上崩溃 - 这两点都在cellForRowAtIndexPath中返回一个单元格。下面我提供了两种方法，我相信事情正在崩溃，以及我的控制台上的错误输出。非常感谢任何帮助或指导，谢谢！
违规方法：
- (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 < 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) && (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] < (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;
}
}
}
}
日志输出：
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 <-- EXC_BAD_ACCESS (code=2, address=0xb0000008)
答案 0 :(得分：2)
在某些地方初始化时，您似乎缺少了cellIdentifier。
static NSString *CellIdentifier = @"EventContentGridViewCell";
EventDetailGridRow *cell = (EventDetailGridRow *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
{
cell = [[EventDetailGridRow alloc] initWithFrame:CGRectMake(0, 0, 306, 102)];//where is CellIdentifier??
应该是这样的，
cell = [[EventDetailGridRow alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
cell.frame = CGRectMake(0, 0, 306, 102);
在为"EventContentGridViewCell"创建对象时，我无法看到cellIdentifier EventDetailGridRow设置。同样的事情适用于上述代码中的所有其他自定义单元类。但是我不确定上述代码中是否存在这个问题。
如果上述更改无法解决您的问题，请查看此How to add a breakpoint to objc_exception_throw?和Stack trace or more info on unhandled exception in Xcode/iPhone。应该帮助您找出问题发生的位置。