how to resolve malloc_error_break? (Xcode Objective C)

Question

Finally

i test on simulator os 3.0 it also show error but

when i try to run on simulator 3.1.3 and 3.2 it not have an error

did anyone explan this ?

after break at malloc_error_break it show callstack like this link text

it show log when rotate device

[Session started at 2010-02-13 19:15:22 +0700.]
2010-02-13 19:15:24.405 iPortals[21656:207] bool for 1
iPortals(21656,0xa0089500) malloc: *** error for object 0x285e000: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
iPortals(21656,0xa0089500) malloc: *** error for object 0x2850000: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
iPortals(21656,0xa0089500) malloc: *** error for object 0x286c000: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
iPortals(21656,0xa0089500) malloc: *** error for object 0x287c000: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug

here is my code

@implementation WebViewController

@synthesize myWebView;
@synthesize AppDelegate;
@synthesize mybanner;
@synthesize request;

- (void)dealloc
{
    //NSLog(@"WebViewController has been dealloc");
    myWebView.delegate = nil;
    self.myWebView = nil;
    [self.myWebView release];
    [super setView:nil];


    [myWebView release];
    myWebView = nil;
    request = nil;

    [mybanner release];
    [super dealloc];
}

- (void)setView:(UIView *)aView
{
    //NSLog(@"setView:(UIView *)aView");
    if (aView == nil) {
        self.myWebView = nil;
    }    
    [super setView:aView];
}

- (void)action {
    AppDelegate = nil;
    AppDelegate = [[UIApplication sharedApplication] delegate];
    [[UIApplication sharedApplication] openURL:[NSURL URLWithString:AppDelegate.PushLink]];
}

- (void)didReceiveMemoryWarning {

    //NSLog(@"didReceiveMemoryWarning: view = %@, superview = %@", [self valueForKey:@"_view"], [[self valueForKey:@"_view"] superview]);
    [super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview
    // Release anything that's not essential, such as cached data
    [[NSURLCache sharedURLCache] removeAllCachedResponses];
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    //NSLog(@"viewDidLoad: view = %@", self.view);
    self.title = NSLocalizedString(@"iPortals", @"");


    //UIBarButtonItem *customItem = [[UIBarButtonItem alloc] initWithTitle:@"Item" style:UIBarButtonItemStyleBordered   target:self action:@selector(action];
    //self.navigationController.toolbar setItems: = [[UIBarButtonItem alloc] initWithTitle:@"[...]" style:UIBarButtonItemStyleBordered target:self action:@selector(action)];

    /*
    UIBarButtonItem *emailButton = [[UIBarButtonItem alloc]
                                    initWithImage:[UIImage imageNamed:@"icon.png"]
                                    style:UIBarButtonItemStylePlain target:self
                                    action:@selector(action)];
    self.toolbarItems = [NSArray arrayWithObjects:emailButton, nil];
    [emailButton release];
    //*/
    AppDelegate = nil;
    AppDelegate = [[UIApplication sharedApplication] delegate];

    //NSLog(@"777777777 %@",AppDelegate.PushLink);
    /*
    CGRect webFrame = [[UIScreen mainScreen] applicationFrame];
    webFrame.origin.y += kTopMargin + 5.0;  // leave from the URL input field and its label
    webFrame.size.height = 400;
    //webFrame.size.height -= 40.0;
    self.myWebView = nil;

    //*/
    //self.myWebView = [[[UIWebView alloc] initWithFrame:webFrame] autorelease];

    self.myWebView.backgroundColor = [UIColor grayColor];
    self.myWebView.scalesPageToFit = YES;
    self.myWebView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight);
    self.myWebView.delegate = self;

    [self.view addSubview: self.myWebView];
    self.mybanner.backgroundColor = [UIColor clearColor];
    [self.view addSubview: self.mybanner];

    /*
    CGRect textFieldFrame = CGRectMake(kLeftMargin, kTweenMargin,
                                       self.view.bounds.size.width - (kLeftMargin * 2.0), kTextFieldHeight);
    UITextField *urlField = [[UITextField alloc] initWithFrame:textFieldFrame];
    urlField.borderStyle = UITextBorderStyleBezel;
    urlField.textColor = [UIColor blackColor];
    urlField.delegate = self;
    urlField.placeholder = @"<enter a URL>";
    urlField.text = AppDelegate.PushLink;
    urlField.backgroundColor = [UIColor whiteColor];
    urlField.autoresizingMask = UIViewAutoresizingFlexibleWidth;
    urlField.returnKeyType = UIReturnKeyGo;
    urlField.keyboardType = UIKeyboardTypeURL;  // this makes the keyboard more friendly for typing URLs
    urlField.autocapitalizationType = UITextAutocapitalizationTypeNone; // don't capitalize
    urlField.autocorrectionType = UITextAutocorrectionTypeNo;   // we don't like autocompletion while typing
    urlField.clearButtonMode = UITextFieldViewModeAlways;
    [urlField setAccessibilityLabel:NSLocalizedString(@"URLTextField", @"")];
    [self.view addSubview:urlField];
    [urlField release];
     */

    request = nil;
    request = [NSURLRequest requestWithURL:[NSURL URLWithString:AppDelegate.PushLink]
                               cachePolicy:NSURLRequestUseProtocolCachePolicy
                           timeoutInterval:60.0];
    [self.myWebView loadRequest:request];
}

// called after the view controller's view is released and set to nil.
// For example, a memory warning which causes the view to be purged. Not invoked as a result of -dealloc.
// So release any properties that are loaded in viewDidLoad or can be recreated lazily.
//
- (void)viewDidUnload
{
    [super viewDidUnload];

    // release and set to nil

    [self.myWebView release];
    self.myWebView = nil;

}

-(BOOL)canBecomeFirstResponder {
    //NSLog(@"canBecomeFirstResponder ");
    return YES;
}

-(void)viewDidAppear:(BOOL)animated {
    //NSLog(@"viewDidAppear ");

    [self becomeFirstResponder];
}

- (void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event {
    //NSLog(@"overrideoverrideoverrideoverrideoverrideoverrideoverrideoverride ");
    if ( event.subtype == UIEventSubtypeMotionShake )
    {
        // Put in code here to handle shake
        AppDelegate = nil;
        AppDelegate = [[UIApplication sharedApplication] delegate];
        [AppDelegate ToggleNavigationBar];
        [AppDelegate playsound:1];
        [self setAdHide:AppDelegate.toggle];

    }
}

- (void)setAdHide:(BOOL)hide {

    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.6];
    if (!hide) {
        if (current == UIInterfaceOrientationLandscapeLeft || current == UIInterfaceOrientationLandscapeRight) {
            [mybanner setFrame:CGRectMake(0, 272, mybanner.frame.size.width, mybanner.frame.size.height)];
        }
        else {
            [mybanner setFrame:CGRectMake(0, 432, mybanner.frame.size.width, mybanner.frame.size.height)];
        }
    }
    else {
        [self restoreAd];
    }
    [UIView commitAnimations];

}

- (void)restoreAd {
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.6];
    [mybanner setFrame:CGRectMake(0, 0, mybanner.frame.size.width, mybanner.frame.size.height)];    
    [UIView commitAnimations];
}

#pragma mark -
#pragma mark UIViewController delegate methods

- (void)viewWillAppear:(BOOL)animated
{
    self.myWebView.delegate = nil;
    self.myWebView.delegate = self; // setup the delegate as the web view is shown
}

- (void)viewWillDisappear:(BOOL)animated
{
    //[self.myWebView removeFromSuperview];
    [self.myWebView stopLoading];   // in case the web view is still loading its content
    self.myWebView.delegate = nil;  // disconnect the delegate as the webview is hidden
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;

}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation 
{
    current = interfaceOrientation;
    [self restoreAd];
    return ((interfaceOrientation == UIInterfaceOrientationLandscapeLeft) || (interfaceOrientation == UIDeviceOrientationPortrait) ||
            (interfaceOrientation == UIInterfaceOrientationLandscapeRight));
}

// this helps dismiss the keyboard when the "Done" button is clicked
- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [textField resignFirstResponder];
    [self.myWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:[textField text]]]];

    return YES;
}


#pragma mark -
#pragma mark UIWebViewDelegate

- (void)webViewDidStartLoad:(UIWebView *)webView
{

    // starting the load, show the activity indicator in the status bar
    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
}

- (void)webViewDidFinishLoad:(UIWebView *)webView
{
    // finished loading, hide the activity indicator in the status bar
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;

}

- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error
{

    // load error, hide the activity indicator in the status bar
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;

    // report the error inside the webview
    //NSString* errorString = [NSString stringWithFormat:
    //                       @"<html><center><font size=+5 color='red'>An error occurred:<br>%@</font></center></html>",
    //                       error.localizedDescription];
    //[self.myWebView loadHTMLString:errorString baseURL:nil];
    //URLCacheAlertWithError(error);
}

@end

Answer 1

That means that you are trying to release an object that was not allocated.

Can you show us your code?

Answer 2

Follow the recommendation in the log message: set a breakpoint in malloc_error_break. When the breakpoint fires, look at the backtrace in Xcode (or use the bt command on the gdb command-line) and see where you're calling free, or API that uses free.

Memory use issues are sometimes discoverable using the Xcode static analyzer - choose "Build and Analyze" from the Xcode build menu.

Answer 3

You seem to be repeatedly trying to dealloc your pointers. In the dealloc method ONLY call [blah release]; and in the viewDidUnload method assign your pointers a nil value. Do not do BOTH in both methods.

- (void)dealloc
{
    [self.myWebView release];
    [mybanner release];
    [super dealloc];
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    self.myWebView = nil;

}

You seem to be missing a few variables as well.

Answer 4

This bothered me a lot once, and thus I wrote a blog post describing how to solve after I found the solution, hope it helps fellows devs:

http://www.drooljunkie.com/code-uncode/beginning-iphone-app-dev-issues-part-3-double-free-errors/