问题
I'm having a problem with some code in the loadView: method of one of my view controllers. Essentially I have a view which centres itself in a larger view (on an iPad) and has some labels, buttons and icons which are programmatically loaded into it.
The problem occurs when the view controller calls the dealloc method, and tries to release. I get a -[CALayer release]: message sent to deallocated instance error and the application crashes.
From reading up about this error, it appears I am over-releasing something, but I don't think that's the case: the code below is the trouble maker and I've tried both autorelease and manual release calls on everything, as well as simply not releasing them (I know, I know, that's bad) but it continues to cause havok.
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];
The container property is released in the dealloc method, as follows:
- (void)dealloc {
[leather release];
[backButton release];
[container release];
[super dealloc];
}
Any answers or suggestions people can provide would be greatly appreciated! I am truly stumped.
回答1:
Profile your application in the simulator with 'Zombies' Instrument.
Run your app for a while and do whatever you have to do to make your app crash. When it does, you will get a pop up like the image below and it will halt the profiling of the app:
Then if you click on the little arrow next to the address (0x158b3c00) .. it will take you to the object retain/release history for the object that was over released (the zombie).
If you highlight the line above where the retain count went to -1, and open View -> Extended detail, it should point you to the stack trace and line in your code where the object was overreleased:
If you double click the class where it is occuring, it will open up your source and show you the bad line of code:
回答2:
The over-releasing could be occurring during the objects life time and not just when they're being created. A few tips:
- use accessors to ensure that pointers are set to
nil - be consistent with your use of
release/autorelease. Personally I prefer to have[[[Class alloc] init] autorelease]all on 1 line. - Learn the difference between
release/autorelease. Let's Build NSAutoreleasePool is a good place to start.
来源：https://stackoverflow.com/questions/7402171/calayer-release-message-sent-to-deallocated-instance