-[CALayer release]：消息发送到已释放的实例

Question

我的视图控制器之一的 loadView: 方法中的某些代码出现问题。本质上，我有一个视图，它以更大的视图（在 iPad 上）为中心，并且有一些标签、按钮和图标以编程方式加载到其中。

当视图控制器调用 dealloc 方法并尝试释放时，就会出现此问题。我收到 -[CALayer release]: message sent to deallocated instance 错误，并且应用程序崩溃。

通过阅读有关此错误的信息，我似乎过度释放了某些内容，但我认为情况并非如此：下面的代码是麻烦制造者，我已经尝试过对所有内容进行自动释放和手动释放调用，以及只是不释放它们（我知道，我知道，这很糟糕），但它继续造成破坏。

container = [[UIView alloc] initWithFrame:CGRectNull];
container.autoresizingMask = ( UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin );
container.frame = CGRectMake( (viewSize.width-320)/2, (viewSize.height-480)/2, 320, 480);
[self.view addSubview:container];

UILabel *welcomeTo = [[[UILabel alloc] initWithFrame:CGRectNull] autorelease];
welcomeTo.backgroundColor = [UIColor clearColor];
welcomeTo.font = [UIFont fontWithName:@"HelveticaNeue-Light" size:18.0];
welcomeTo.frame = CGRectMake(23, 15, 103, 24);
welcomeTo.shadowColor = [UIColor blackColor];
welcomeTo.shadowOffset = CGSizeMake( 0, 1 );
welcomeTo.text = @"Welcome to";
welcomeTo.textAlignment = UITextAlignmentLeft;
welcomeTo.textColor = [UIColor colorWithWhite:1.0 alpha:0.6];
[container addSubview:welcomeTo];

UILabel *progressions = [[[UILabel alloc] initWithFrame:CGRectNull] autorelease];
progressions.backgroundColor = [UIColor clearColor];
progressions.font = [UIFont fontWithName:@"HelveticaNeue-BoldItalic" size:44.0];
progressions.frame = CGRectMake(20, 30, 280, 56);
progressions.shadowColor = [UIColor blackColor];
progressions.shadowOffset = CGSizeMake( 0, 1 );
progressions.text = @"Progressions";
progressions.textAlignment = UITextAlignmentCenter;
progressions.textColor = [UIColor colorWithWhite:1.0 alpha:0.6];
[container addSubview:progressions];

UILabel *blurb = [[[UILabel alloc] initWithFrame:CGRectNull] autorelease];
blurb.backgroundColor = [UIColor clearColor];
blurb.font = [UIFont fontWithName:@"HelveticaNeue" size:14.0];
blurb.frame = CGRectMake(23, 100, 274, 51);
blurb.numberOfLines = 3;
blurb.shadowColor = [UIColor blackColor];
blurb.shadowOffset = CGSizeMake( 0, 1 );
blurb.text = @"Kick off the fun by adding some content, or if you're not sure what you're doing, check out the \"Getting Started\" guide!";
blurb.textAlignment = UITextAlignmentLeft;
blurb.textColor = [UIColor colorWithWhite:1.0 alpha:0.6];
[container addSubview:blurb];

UIButton *button1 = [[UIButton alloc] initWithFrame:CGRectMake(20, 170, 280, 88)];
[button1 setBackgroundImage:[UIImage imageNamed:@"emptyButtonLarge.png"] forState:UIControlStateNormal];
[button1 setBackgroundImage:[UIImage imageNamed:@"emptyButtonLargeHighlighted.png"] forState:UIControlStateHighlighted];
[button1 addTarget:self action:@selector(createChart:) forControlEvents:UIControlEventTouchUpInside];
[container addSubview:button1];
[button1 release];

UIImageView *icon1 = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"addchart.png"]];
icon1.frame = CGRectMake(30, 180, icon1.frame.size.width, icon1.frame.size.height);
[container addSubview:icon1];
[icon1 release];

UILabel *button1title = [[[UILabel alloc] initWithFrame:CGRectMake(110, 185, 180, 20)] autorelease];
button1title.backgroundColor = [UIColor clearColor];
button1title.font = [UIFont boldSystemFontOfSize:17.0];
button1title.shadowColor = [UIColor blackColor];
button1title.shadowOffset = CGSizeMake( 0, 1 );
button1title.text = @"Create a Chart";
button1title.textAlignment = UITextAlignmentLeft;
button1title.textColor = [UIColor colorWithWhite:1.0 alpha:0.6];
[container addSubview:button1title];

UILabel *button1blurb = [[[UILabel alloc] initWithFrame:CGRectMake(110, 205, 180, 40)] autorelease];
button1blurb.backgroundColor = [UIColor clearColor];
button1blurb.font = [UIFont systemFontOfSize:13.0];
button1blurb.numberOfLines = 2;
button1blurb.shadowColor = [UIColor blackColor];
button1blurb.shadowOffset = CGSizeMake( 0, 1 );
button1blurb.text = @"A cheat sheet for a displaying a song in any key.";
button1blurb.textAlignment = UITextAlignmentLeft;
button1blurb.textColor = [UIColor colorWithWhite:1.0 alpha:0.6];
[container addSubview:button1blurb];

UIButton *button2 = [[UIButton alloc] initWithFrame:CGRectMake(20, 270, 280, 88)];
[button2 setBackgroundImage:[UIImage imageNamed:@"emptyButtonLarge.png"] forState:UIControlStateNormal];
[button2 setBackgroundImage:[UIImage imageNamed:@"emptyButtonLargeHighlighted.png"] forState:UIControlStateHighlighted];
[button2 addTarget:self action:@selector(createSet:) forControlEvents:UIControlEventTouchUpInside];
[container addSubview:button2];
[button2 release];

UIImageView *icon2 = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"addset.png"]];
icon2.frame = CGRectMake(30, 280, icon2.frame.size.width, icon2.frame.size.height);
[container addSubview:icon2];
[icon2 release];

UILabel *button2title = [[[UILabel alloc] initWithFrame:CGRectMake(110, 285, 180, 20)] autorelease];
button2title.backgroundColor = [UIColor clearColor];
button2title.font = [UIFont boldSystemFontOfSize:17.0];
button2title.shadowColor = [UIColor blackColor];
button2title.shadowOffset = CGSizeMake( 0, 1 );
button2title.text = @"Create a Set";
button2title.textAlignment = UITextAlignmentLeft;
button2title.textColor = [UIColor colorWithWhite:1.0 alpha:0.6];
[container addSubview:button2title];

UILabel *button2blurb = [[[UILabel alloc] initWithFrame:CGRectMake(110, 305, 180, 40)] autorelease];
button2blurb.backgroundColor = [UIColor clearColor];
button2blurb.font = [UIFont systemFontOfSize:13.0];
button2blurb.numberOfLines = 2;
button2blurb.shadowColor = [UIColor blackColor];
button2blurb.shadowOffset = CGSizeMake( 0, 1 );
button2blurb.text = @"A collection of charts that can be displayed like a book.";
button2blurb.textAlignment = UITextAlignmentLeft;
button2blurb.textColor = [UIColor colorWithWhite:1.0 alpha:0.6];
[container addSubview:button2blurb];

UIButton *button3 = [[UIButton alloc] initWithFrame:CGRectMake(20, 370, 280, 40)];
[button3 setBackgroundImage:[UIImage imageNamed:@"emptyButtonSmall.png"] forState:UIControlStateNormal];
[button3 setBackgroundImage:[UIImage imageNamed:@"emptyButtonSmallHighlighted.png"] forState:UIControlStateHighlighted];
[button3 addTarget:self action:@selector(gettingStarted:) forControlEvents:UIControlEventTouchUpInside];
[container addSubview:button3];
[button3 release];

UILabel *button3title = [[[UILabel alloc] initWithFrame:CGRectMake(20, 370, 280, 36)] autorelease];
button3title.backgroundColor = [UIColor clearColor];
button3title.font = [UIFont boldSystemFontOfSize:17.0];
button3title.shadowColor = [UIColor blackColor];
button3title.shadowOffset = CGSizeMake( 0, 1 );
button3title.text = @"Getting Started";
button3title.textAlignment = UITextAlignmentCenter;
button3title.textColor = [UIColor colorWithWhite:1.0 alpha:0.6];
[container addSubview:button3title];

UILabel *version = [[[UILabel alloc] initWithFrame:CGRectMake(20, 420, 280, 20)] autorelease];
version.backgroundColor = [UIColor clearColor];
version.font = [UIFont fontWithName:@"HelveticaNeue-Light" size:12.0];
version.shadowColor = [UIColor blackColor];
version.shadowOffset = CGSizeMake( 0, 1 );
version.text = [NSString stringWithFormat:@"Version v%@ (%@)", [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleVersion"], kRevisionNumber];
version.textAlignment = UITextAlignmentCenter;
version.textColor = [UIColor colorWithWhite:1.0 alpha:0.6];
[container addSubview:version];

容器属性是在 dealloc 方法中释放的，如下所示：

- (void)dealloc {
    [leather release];
    [backButton release];
    [container release];
    [super dealloc];
}

如果有人能提供任何答案或建议，我们将不胜感激！我真的很难过。

Answer 1

使用“僵尸”仪器在模拟器中分析您的应用程序。

运行你的应用程序一段时间，然后做任何你必须做的事情来让你的应用程序崩溃。当它出现时，您将看到如下图所示的弹出窗口，并且它将停止应用程序的分析：

然后，如果您单击地址（0x158b3c00）旁边的小箭头..它将带您到过度释放的对象（僵尸）的对象保留/释放历史记录。

如果突出显示上面保留计数变为 -1 的行，然后打开“视图”->“扩展详细信息，它应该指向您的堆栈跟踪和代码中对象被过度释放的行：

如果您双击发生该问题的类，它将打开您的源代码并显示错误的代码行：

Answer 2

过度释放可能发生在对象的生命周期内，而不仅仅是在创建对象时。一些提示：

• 使用访问器确保指针设置为 nil
• 与您对 release/autorelease 的使用保持一致。就我个人而言，我更喜欢将 [[[Class alloc] init] autorelease] 全部放在 1 行中。
• 了解 release/autorelease 之间的区别。 让我们构建 NSAutoreleasePool 是个好地方开始。

Answer 3

对于那些即使使用 ARC 也遇到此错误的人来说，已解决
（不需要手动“释放”变量）

• 在我的例子中，问题是在我的函数声明中[第1159行]我写道我将返回一个 String/NSString ，并且我忘记在 [第 1212 行] 上写下返回值，如下所示：

  <块引用>

  返回@"";

将其添加到[第 1212 行]就足以“解决问题”。

PS：请注意，会发生此运行时错误（而不是构建应用程序时的编译错误），因为在[第 1203 行]上我创建/启动了一个异步代码块，这取决于如何我写它可以返回我的函数所需的字符串（我也没有这样做，所以这就是发生这个错误的原因。