发送到已释放实例问题的消息
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【中文标题】发送到已释放实例问题的消息【英文标题】:message sent to deallocated instance issue 【发布时间】:2011-05-29 01:46:53 【问题描述】:过去几个小时我一直在调试以下问题,但似乎无法得出一个好的结论。
-[NSIndexPath row]:消息发送到deallocated instance 0x506cf90
我正在 UITableView 上的每个单元格上实现滑动识别器。每当检测到滑动时,都会调用下面的代码。它的作用是在单元格中显示/隐藏子视图。如果子视图已经显示,则隐藏,否则显示。如果单元格 5 上已经显示了子视图,并且在单元格 3 上检测到滑动,那么我们首先删除该子视图,然后在单元格 3 上添加子视图。
我尝试了下面的代码,它似乎适用于某些单元格。但是,特别是在 UITableView 底部有一个单元格,如果我尝试隐藏子视图,它会给我上面的错误。它对另一个单元格工作得很好,只是底部的单元格。这是为什么呢?
代码如下:
- (void)swipe:(UISwipeGestureRecognizer *)recognizer direction:(UISwipeGestureRecognizerDirection)direction
if (recognizer && recognizer.state == UIGestureRecognizerStateEnded)
// Get the table view cell where the swipe occured
CGPoint location = [recognizer locationInView:self.table];
NSIndexPath* indexPath = [self.table indexPathForRowAtPoint:location];
ConvoreCell* cell = (ConvoreCell *) [self.table cellForRowAtIndexPath:indexPath];
[self.table beginUpdates];
NSLog(@"ROW is %d", global.row);
//removing the options view at the other cell before adding a new one
if (global != nil && global.row != indexPath.row)
[sideSwipeView removeFromSuperview];
[sideSwipeView release];
sideSwipeView = nil;
//options already exist, we need to remove it
if (sideSwipeView != nil)
[sideSwipeView removeFromSuperview];
[sideSwipeView release];
sideSwipeView = nil;
slide = NO;
else
//options do not exist and therefore we need to add it
NSArray * buttonData = [[NSArray arrayWithObjects:
[NSDictionary dictionaryWithObjectsAndKeys:@"Mark Read", @"title", @"mark.png", @"image", nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Track", @"title", @"play.png", @"image", nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Leave", @"title", @"delete.png", @"image", nil],
nil] retain];
NSMutableArray * buttons = [[NSMutableArray alloc] initWithCapacity:buttonData.count];
sideSwipeView = [[UIView alloc] initWithFrame:CGRectMake(0, cell.frame.size.height-25, 320, 25)];
[sideSwipeView setAutoresizingMask:UIViewAutoresizingFlexibleTopMargin];
[sideSwipeView setBackgroundColor:[UIColor colorWithPatternImage: [UIImage imageNamed:@"dotted-pattern.png"]]];
[sideSwipeView setTag:-10];
CGFloat leftEdge = BUTTON_LEFT_MARGIN;
for (NSDictionary* buttonInfo in buttonData)
if (!([[buttonInfo objectForKey:@"title"] isEqualToString:@"Mark Read"] && [[[groups objectAtIndex:indexPath.row] unread] intValue] == 0))
UIButton* button = [UIButton buttonWithType:UIButtonTypeCustom];
button.autoresizingMask = UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleTopMargin;
UIImage* buttonImage = [UIImage imageNamed:[buttonInfo objectForKey:@"image"]];
if ([[[groups objectAtIndex:indexPath.row] tracked] intValue] == 1 && [[buttonInfo objectForKey:@"title"] isEqualToString:@"Track"])
buttonImage = [UIImage imageNamed:@"pause.png"];
[button setSelected:YES];
else
[button setSelected:NO];
button.frame = CGRectMake(leftEdge, 0, buttonImage.size.width, buttonImage.size.height);
UIImage* grayImage = [self imageFilledWith:[UIColor colorWithWhite:0.9 alpha:1.0] using:buttonImage];
[button setImage:grayImage forState:UIControlStateNormal];
if ([[buttonInfo objectForKey:@"title"] isEqualToString:@"Mark Read"])
[button addTarget:self action:@selector(markRead:) forControlEvents:UIControlEventTouchUpInside];
else if ([[buttonInfo objectForKey:@"title"] isEqualToString:@"Track"])
[button addTarget:self action:@selector(track:) forControlEvents:UIControlEventTouchUpInside];
else if ([[buttonInfo objectForKey:@"title"] isEqualToString:@"Leave"])
[button addTarget:self action:@selector(leave:) forControlEvents:UIControlEventTouchUpInside];
[button setTag:indexPath.row];
[buttons addObject:button];
[sideSwipeView addSubview:button];
leftEdge = leftEdge + buttonImage.size.width + BUTTON_SPACING;
[cell.contentView addSubview:sideSwipeView];
[buttons release];
[buttonData release];
global = indexPath;
slide = YES;
[self.table endUpdates];
[self.table deselectRowAtIndexPath:indexPath animated:YES];
现在这里的问题是指向 indexPath 的指针不知何故被释放了。我能够通过制作 indexPath 的副本而不是仅仅引用指针来解决这个问题。所以我做了:
global = [indexPath copy];
由于某种原因,在调用此方法后,它会释放 indexPath,我不确定是谁做的。我认为 ios 做的...是真的吗?
【问题讨论】:
【参考方案1】: NSIndexPath* indexPath = [self.table indexPathForRowAtPoint:location];
返回一个自动释放的实例。所以,是的,您对global
的分配需要保留该对象。 copy
有效地返回一个保留的实例。
不过,不要泄漏。如果你这样做:
global = [indexPath copy];
而且你不先释放global
的原始值,你会泄漏。
哦,还有:http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/MemoryMgmt/MemoryMgmt.html
【讨论】:
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